UPDATED 10.06AM: Russia has dramatically escalated its air war in Syria, unleashing heavy bombardments and cruise missile strikes from the Caspian Sea as cover for a major Syrian army ground offensive against rebels.

Russian President Vladimir Putin said Moscow had begun synchronising its strikes with the army's ground movements as the Kremlin voiced willingness to make contact with Western-backed rebels that Washington and its allies accuse it of targeting.

Putin, who turned 63 on Wednesday, said Russian warships had fired cruise missiles on Islamic State group positions in Syria for the first time.

A video map released by Russia's defence ministry showed the missiles launched from warships in the southern Caspian Sea and flying close to 1500 kilometres through Iranian and Iraqi airspace before hitting targets in Syria.

A Syrian military source told AFP government troops had begun a broad ground operation on Wednesday near the village of Latmeen in Hama province, aided by Russian air cover.
The US State Department says almost none of Russia's military strikes have been aimed at the Islamic State group or jihadists tied to al-Qaeda, with most targeting the Syrian opposition.

"Greater than 90 per cent of the strikes that we've seen them take to date have not been against ISIL or Al-Qaeda-affiliated terrorists," spokesman John Kirby said on Wednesday.

"They've been largely against opposition groups that want a better future for Syria and don't want to see the Assad regime stay in power."

The Syrian Observatory for Human Rights reported at least 40 Russian air strikes in Hama and neighbouring Idlib province, which is controlled by the powerful Army of Conquest alliance that includes al-Qaeda affiliate Al-Nusra Front.

The alliance has sought to expand into Hama from Idlib and seize high ground to target the neighbouring regime stronghold of Latakia province.

The Britain-based Observatory said "many raids, believed to be from Russian warplanes, killed six people" including two children in Maraat al-Numan in Idlib.

AFP has concluded after a careful reading of Russia's video map that at least one cruise missile struck near the IS-held city of Al-Bab in Aleppo province, while several others appeared to head towards targets in Idlib.

Russia says its forces have hit 112 targets since its operations in Syria - which it insists target IS and other "terrorist groups" - began on September 30.
But Syrian rebels and their backers say a range of opposition fighters, not just jihadists, have been hit.
The US-backed Suqur al-Jabal rebel group in the northern province of Aleppo said Wednesday its arms depots had been destroyed in Russian raids.

Turkey's Prime Minister Ahmet Davutoglu alleged that just two out of 57 Russian strikes examined by Turkish intelligence had hit IS.

The Russian campaign has raised hackles in Ankara, which accuses Moscow of violating its airspace from Syria on at least two occasions over the weekend.

It also reported a violation by a MIG-29 jet of unknown nationality on Monday.