Confusion reigned in Moscow, and around the world, on Tuesday night when Vladimir Putin failed to turn up for a flagged speech that could have heralded a dramatic escalation in the war against Ukraine.

At 8pm Moscow time (5am Wednesday NZT) Putin was expected to announce his backing of public votes in occupied areas of Ukraine which would lead to them being declared Russian territory.

If so, it would be major escalation of what the Russian President calls the "special military operation". The Kremlin could then decide that any attacks on occupied Ukraine were attacks on Russia itself.

Putin was also expected to announce some form of conscription to bolster Russian forces.

But 8pm came and went, and then 9pm and then 10pm. Local news services – which had said the speech was occurring – quietly removed the notices.

On Russia 1, the country's leading TV channel, a film about a volleyball team was played.

Multiple reports have now said the speech had been postponed, perhaps until Wednesday. But the rumour mill has gone into overdrive as to why The Kremlin would flag potentially a hugely important speech only for it not to happen.

Referendum threat

In advance of Putin's announcement, world leaders, including those close to Putin, had condemned the move to recognise occupied regions of Ukraine.

Turkish President Recep Tayyip Erdoğan, who had earlier said Putin wanted to end the war "as soon as possible," added later on Tuesday that it would not recognise the results of any referendum.

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The moves comes as Ukraine has recaptured large tracts of land in eastern parts of the country which is thought to have panicked Moscow.

Russian occupying authorities in the Donbas regions of Donetsk and Luhansk as well as the southern regions of Kherson and Zaporizhzhia said referendums should be held immediately on the areas becoming part of Russia.

Russian-controlled regions of eastern and southern Ukraine have announced plans to start voting this week to become integral parts of Russia.

The concerted and quickening Kremlin-backed efforts to swallow up four regions could set the stage for Moscow to escalate the war after Ukrainian successes on the battlefield.

The scheduling of referendums starting Friday came after a close ally of Putin said the votes are needed and as Moscow is losing ground in the invasion it began nearly seven months ago, increasing pressure on the Kremlin for a stiff response.

Former President Dmitry Medvedev, the deputy head of Russia's Security Council chaired by Putin, said referendums that fold regions into Russia would make redrawn frontiers "irreversible" and enable Moscow to use "any means" to defend them.

Emergency workers carry bodies to a refrigerator truck after their exhumation in the recently retaken area of Izium. Photo / Evgeniy Maloletka, AP

The votes, in territory Russia already controls, are all but certain to go Moscow's way but are unlikely to be recognised by Western governments who are backing Ukraine with military and other support that has helped its forces seize momentum on battlefields in the east and south.

Ukrainian Foreign Minister Dmytro Kuleba denounced the referendums as a sham and tweeted that "Ukraine has every right to liberate its territories and will keep liberating them whatever Russia has to say".

US national security adviser Jake Sullivan slammed the planned votes.

"We will never recognise this territory as anything other than part of Ukraine," he said, adding that they reflect Russia's setbacks on the battlefield.

"These are not the actions of a confident country. These are not acts of strength," he said.

In New York, where he is attending the UN General Assembly, German Chancellor Olaf Scholz said: "It is very, very clear that these sham referendums cannot be accepted".

Latvian Foreign Minister Edgars Rinkevics called for more sanctions against Russia and more weapons for Ukraine, tweeting: "We must say no to Russian blackmail".

In Donetsk, part of Ukraine's wider Donbas region that has been gripped by rebel fighting since 2014 and which Putin has set as a primary objective of the invasion, separatist leader Denis Pushilin said the vote will "restore historic justice" to the territory's "long-suffering people".

They "have earned the right to be part of the great country that they always considered their motherland", he said.

In partly Russian-occupied Zaporizhzhia, pro-Russia activist Vladimir Rogov said: "The faster we become part of Russia, the sooner peace will come".

Local residents collect wood for heating from a destroyed school where Russian forces were based, in the recently retaken area of Izium. Photo / Evgeniy Maloletka, AP

Former Kremlin speechwriter and Russian political analyst Abbas Gallyamov said on Facebook that Moscow-backed separatists appeared "scared that the Russians will abandon them" amid the Ukrainian offensive and forged ahead with referendum plans to force the Kremlin's hand.

In another signal that Russia is digging in for a protracted and possibly ramped-up conflict, the Kremlin-controlled lower house of parliament voted Tuesday to toughen laws against desertion, surrender and looting by Russian troops. Lawmakers also voted to introduce possible 10-year prison terms for soldiers refusing to fight. If approved, as expected, by the upper house and then signed by Putin, the legislation would strengthen commanders' hands against failing morale reported among soldiers.

In the Russian-occupied city of Enerhodar, shelling Tuesday around Europe's largest nuclear power plant damaged a cooling system, a dining hall for staff and an unspecified "special building", the city administration said. There were no further details about the damage.

The Zaporizhzhia Nuclear Power Plant has been a focus of concern for months because of fears that shelling could lead to a radiation leak. Russia and Ukraine each blame the other for the shelling.

Kremlin spokesman Dmitry Peskov said there are no prospects for a diplomatic settlement of the conflict. Medvedev, who served as Russia's president from 2008-2012, said on his messaging app channel that the referendums are important to protect their residents and would "completely change" Russia's future trajectory.

"After they are held and the new territories are taken into Russia's fold, a geopolitical transformation of the world will become irreversible," Medvedev said.

"An encroachment on the territory of Russia is a crime that would warrant any means of self-defence," he said, adding that Russia would enshrine the new territories in its constitution so no future Russian leader could hand them back.

People receive packages from their relatives in the recently retaken area of Izium, Ukraine. Photo / Evgeniy Maloletka, AP

"That is why they fear those referendums so much in Kyiv and in the West," Medvedev said. "That is why they must be held."

Ukrainian analyst Volodymyr Fesenko, head of the independent Penta Centre think-tank in Kyiv, said the Kremlin hopes the votes and the possibility of military escalation will raise the pressure from Western governments for Ukrainian President Volodymyr Zelenskyy to start talks with Moscow.

The move "reflects the weakness, not the strength of the Kremlin, which is struggling to find levers to influence the situation that has increasingly spun out of its control", he said.

The recapturing of territory, most notably in the northeastern Kharkiv region, has strengthened Ukraine's arguments that its troops could deliver more stinging defeats to Russia with additional armament deliveries.

More heavy weaponry is on its way, with Slovenia promising 28 tanks and Germany pledging four additional self-propelled howitzers. More aid also is expected from Britain, already one of Ukraine's biggest military backers after the US. British Prime Minister Liz Truss is expected to promise that her government will next year "match or exceed" the £2.3 billion ($4.4b) in military aid given to Ukraine this year.

The swiftness of the Ukrainian counteroffensive also led Russian forces to abandon armoured vehicles and other weapons as they hastily retreated. Ukrainian forces are recycling the captured weaponry back into battle. A Washington-based think tank, The Institute for the Study of War, said abandoned Russian T-72 tanks are being used by Ukrainian forces seeking to push into Russian-occupied Luhansk.

Grenades and ammunition on the floor at a destroyed school where Russian forces were based in the recently retaken area of Izium. Photo / Evgeniy Maloletka, AP

After the counteroffensive, Ukrainian officials found hundreds of graves near the once-occupied city of Izium. Yevhenii Yenin, a deputy minister in Ukraine's Internal Affairs Ministry, told a national telecast that officials found many bodies "with signs of violent death".

"These are broken ribs and broken heads, men with bound hands, broken jaws and severed genitalia," he said.

Meanwhile, Ukraine's southern military command said its troops sank a Russian barge carrying troops and weapons across the Dnieper River near the Russian-occupied city of Nova Kakhovka. It offered no other details on the attack in the Russian-occupied Kherson region, which has been a major target in the Ukrainian counteroffensive.

In other developments:

• Ukraine's presidential office said fresh shelling killed three civilians and injured 19 more in a 24-hour span
• Moscow has likely moved its Kilo-class submarines from their station on the Crimean Peninsula to southern Russia over fears about them being struck by long-range Ukrainian fire, the British military said
• McDonald's restaurants in Kyiv began serving again for the first time since the invasion, offering only delivery service initially but marking a step of sorts back towards the life Ukrainians knew before the war.