DONALD TRUMP HAS been criticised after proposing an unfounded conspiracy theory about a 75-year-old protester in New York state who was pushed over by police last week.

The president sided with police over protesters who have taken to the streets across the country, and tweeted that the confrontation involving the protester could have been a “set-up”.

He sought to cast doubt on video footage showing police in the city of Buffalo shoving the man, who fell backwards and hit his head on the pavement last week.

Two police officers have been charged with second-degree assault for the incident and could face prison sentences of up to seven years if convicted. They have pleaded not guilty.

The video is one of several that have emerged in recent weeks showing police using seemingly excessive force against protesters demanding justice and racial equality following the killing of George Floyd.

“Buffalo protester shoved by Police could be an Antifa provocateur,” Trump tweeted.

“75 year old Martin Gugino was pushed away after appearing to scan police communications in order to black out the equipment. @OANN I watched, he fell harder than was pushed. Was aiming scanner. Could be a set up?”

There is no evidence to back Trump’s claim, which referenced a report on One America News Network, a far-right news channel that he often praises.

As he has tried to malign violent protesters as “radical-left, bad people” engaging in domestic terrorism, Trump has repeatedly invoked the label “antifa”, an umbrella term for leftist militants bound more by belief than organisational structure.

Federal law enforcement officials have offered little evidence that antifa-aligned protesters could be behind a movement that has appeared nearly simultaneously in hundreds of cities and towns in all 50 states since Floyd’s death.

Gugino, who is out of intensive care but remains in hospital, has been described by friends as a retiree and veteran peace activist driven by his faith and a desire for social justice.

He is involved with the Western New York Peace Centre and Latin American Solidarity Committee, said Vicki Ross, the centre’s executive director.

She said he has also been undergoing chemotherapy for cancer.

Gugino’s lawyer, Kelly Zarcone, told the Associated Press that Trump’s accusations were “utterly baseless and ridiculous”.

She said her client “has always been a peaceful protester because he cares about today’s society”.

“No one from law enforcement has even suggested anything otherwise, so we are at a loss to understand why the president of the United States would make such dark, dangerous, and untrue accusations about him. We can confirm that those accusations are utterly baseless and ridiculous,” she said.

The number two Republican in the Senate, John Thune, also criticised Mr Trump’s tweet.

“It’s a serious accusation, which should only be made with facts and evidence. And I haven’t seen any yet,” he told reporters.

New York’s Democratic governor Andrew Cuomo called on Mr Trump to apologise for a “wholly unacceptable” tweet.

He said: “How reckless, how irresponsible, how mean, how crude. I mean if there was ever a reprehensible, dumb comment, and from the president of the United States.