A video distributed by the Trump administration to support its argument for banning CNN reporter Jim Acosta from the White House appears to have been doctored, an independent expert said.

White House press secretary Sarah Sanders tweeted the video, which shows Mr Acosta asking a question to President Donald Trump on Wednesday as an intern tries to take his microphone away.

But a frame-by-frame comparison with an Associated Press video of the same incident shows that the one tweeted by Ms Sanders appears to have been altered to speed up Mr Acosta’s arm movement as he touches the intern’s arm, according to Abba Shapiro, an independent video producer.

Earlier, Mr Shapiro noticed that frames in the tweeted video were frozen to slow down the action, allowing it to run to the same length as the AP one.

The alteration is “too precise to be an accident”, said Mr Shapiro, who trains instructors to use the software. The tweeted video also does not have any audio, which Mr Shapiro said would make it easier to alter.

Ms Sanders, who has not said where the tweeted video came from, said it clearly shows Mr Acosta made contact with the intern.

While the origin of the manipulated video is unclear, its distribution marked a new low for an administration that has been criticised for its willingness to mislead.

The White House News Photographers Association decried the sharing of the video.

“As visual journalists, we know that manipulating images is manipulating truth,” said Whitney Shefte, the association’s president.

“It’s deceptive, dangerous and unethical. Knowingly sharing manipulated images is equally problematic, particularly when the person sharing them is a representative of our country’s highest office with vast influence over public opinion.”

“The irony of this White House video involving Jim Acosta is that if it is found to be doctored, it will show the administration to be doing what it accuses the news media of doing — engaging in fake information,” said Aly Colon, a professor in journalism ethics at Washington & Lee University.

CNN has labelled Ms Sanders’s characterisation of Mr Acosta’s exchange with the intern as a lie.

Its position has been supported by witnesses including Reuters White House correspondent Jeff Mason, who was next to Mr Acosta during the news conference and tweeted that he did not see Mr Acosta place his hands on the White House employee. Rather, he said he saw him holding on to the microphone as she reached for it.

Several journalists and organisations — including the American Society of News Editors, the Associated Press Media Editors and the Online News Association — demanded Mr Acosta’s press pass be reinstated.

“It is the essential function of a free press in every democracy to independently gather and report information in the public interest, a right that is enshrined in the First Amendment,” said Julie Pace, AP’s Washington bureau chief. “We strongly reject the idea that any administration would block a journalist’s access to the White House.”

A White House aide reached for the microphone from CNN’s Jim Acosta (Evan Vucci/AP)

Despite losing his White House pass, Mr Acosta is expected to travel to Paris this weekend to cover Mr Trump’s trip to meet world leaders.