Doubts have been raised about the alleged assassination attempt on Venezuelan president Nicolas Maduro.

The world leader was addressing a crowd on Saturday in the crisis-hit capital of Caracas when, according to the government's Information Minister Jorge Rodriguez, several drones with explosives detonated above the leader.

But questions have been asked over whether the whole thing was an inside job staged to concentrate the leader's power.

Reports noted TV cameras failed to capture any footage of bomb-rigged devices or missiles. No such footage emerged on social media either.

Phil Gunson, a consultant with non-profit Crisis Group, said this narrative was all too familiar for the Venezuelan Government.

Firefighters have also disputed the government's version of events, denying there was an assassination attempt on the leader.

Three officials who spoke on condition of anonymity said the incident was actually a gas tank explosion inside an apartment.

Smoke could be seen coming out of a building window at the site of the incident.

However, some witnesses claimed they saw drone devices flying along the street hovering over a residential street and then heard a forceful explosion.

Maerum Gonzalez said she ran in terror to her fifth-floor balcony and then heard a second explosion and saw smoke rising.

"It was so strong the building shook," she said.

"I said, 'Oh my God, what happened?' It terrified me."

Another witness showed the Associated Press mobile phone video of a drone hovering over the street and then crashing into a building.

The witness, who did not want to be identified for fear of reprisal, said he then saw the drone fall to the ground, setting off an explosion.

The witness said he saw police arrest a man purported to be piloting the drone.

David Smilde, a senior fellow at the Washington Office on Latin America, said staging such a scene would make the President look weak.

But he did note Mr Maduro had much to gain from it.

"He will use it to concentrate power, whoever did this," Smilde told AP. "He'll use it to further restrict liberty and purge the government and armed forces."

No one has claimed responsibility for the attack.

Terrifying moment explosions are heard

The response to the alleged attack was broadcast by state news network NTN24 Venezuela.

The footage shows Mr Maduro standing alongside his wife, Cilia Flores, while he gives a speech on the country's economy.

A loud bang sounds off-camera, and he abruptly stops speaking and gazes upwards, looking startled.

A group of bodyguards then rapidly swoop in with shields to escort the leader to safety with what appear to be bulletproof sheets.

The footage also shows hundreds of soldiers lined up as part of the procession on Avenue Bolivar, who run off in different directions after the explosion occurs.

The broadcast is then abruptly cut off.

Mr Maduro had been giving a speech during the celebration of the Nation Guard's 81st anniversary, wearing the presidential banner.

"To the conscious Venezuela, we are going to bet for the good of our country, the hour of the economic recovery has come and we need ...' Mr Maduro was saying before the cameras suddenly moved away from him.

The President was unharmed, but Mr Rodriguez said seven National Guard soldiers were injured in the explosion.

Far-right and US blamed for 'Assassination' attempt

The Venezuelan Government has arrested six "terrorists and hired killers" over their alleged involvement, with Mr Maduro warning the perpetrators face "maximum punishment".

Investigators searched a blackened apartment building on Sunday, where witnesses described seeing a drone and then hearing a thunderous explosion.

Appearing back on state television a few hours after the incident, Mr Maduro said the explosions were part of an "assassination" attempt.

"It was an attack to kill me, they tried to assassinate me today," he said, speaking of a "flying object exploded in front of me".

Mr Maduro accused neighbouring Colombia and unidentified "financiers" in the United States for the attack.

"I have no doubt that the name (Colombian President) Juan Manuel Santos is behind this attack," he said, though providing no evidence to back up his assertion.

Colombia denied the claims, saying they were "baseless".

He added that initial investigations "indicate that various of those financing it live in the United States, in the state of Florida".

"I hope that President Donald Trump is ready to fight these terrorist groups," he said.

Mr Rodriguez described the incident as an attempted hit job on the socialist leader.

"This is an attack against President Nicolas Maduro," he said in a brief televised appearance after the event. "All of the work we have done immediately after has allowed us to establish with evidence that it was an assassination attempt," he said.

"Whoever carried out this attack failed."

Venezuela's government routinely accuses opposition activists of plotting to attack and overthrow the president.

Iron-fisted rule

The parade Mr Maduro attended was to mark the one-year anniversary of the Constitutional Assembly, a legislative body packed with Mr Maduro loyalists who arrogated powers from the opposition-ruled National Assembly.

The head of the assembly, Diosdado Cabello, tweeted that Mr Maduro and the assembled military chiefs had survived a "terrorist attack" he blamed on the opposition.

"The right insists on violence to take areas it can't through votes," he wrote.

Mr Maduro has remained in power over Venezuela, a major oil exporting nation, despite a collapsing economy and a long-running political crisis which has seen his country isolated internationally.

Hundreds of thousands of Venezuelans have fled the country, where food and medicine are in very short supply, and where inflation this year could reach as high as one million per cent according to the International Monetary Fund.

Mr Maduro, a 55-year-old socialist leader who took over from his late mentor Hugo Chavez in 2013, has effectively sidelined the fractured opposition through control of the courts and the electoral body — and unflinching support from the military, which holds key posts in his government.

Mr Maduro often accuses the opposition and the United States of working together to form a "coup" to topple him.

He says the economic malaise gripping Venezuela is an "economic war" and any unrest is plotted by foreign powers.