More than 450 former federal prosecutors have signed a letter saying Donald Trump would have been charged with obstruction of justice if he were anyone other than the president.

The letter was signed by former Justice Department prosecutors who served under Democratic and Republican administrations.

It was released by Protect Democracy, an advocacy group formed two years ago which is critical of the Trump administration.

The former prosecutors say special counsel Robert Mueller’s report “describes several acts that satisfy all of the elements for an obstruction charge”.

Those actions include Mr Trump’s efforts to have Mr Mueller fired, his attempts to limit the scope of the Russia investigation, and tweets and public statements aimed at discouraging aides from co-operating with prosecutors.

READ MORE: Donald Trump claims victory as Mueller report is unable to lay charge of obstruction of justice 

“In our system, every accused person is presumed innocent and it is always the government’s burden to prove its case beyond a reasonable doubt,” the letter says. “But, to look at these facts and say that a prosecutor could not probably sustain a conviction for obstruction of justice — the standard set out in Principles of Federal Prosecution — runs counter to logic and our experience.”

Robert MuellerRobert Mueller (Cliff Owen/AP)

Mr Mueller examined nearly a dozen acts by the president for potential obstruction of justice.

He ultimately reached no conclusion on whether Mr Trump had criminally obstructed justice, citing in part an opinion from the department’s Office of Legal Counsel that says a sitting president cannot be indicted.

Attorney general William Barr and deputy attorney Rod Rosenstein then stepped in and determined Mr Mueller’s evidence was insufficient for an obstruction charge.

Mr Trump has used that finding to claim that the report found no obstruction, but the ex-prosecutors make clear that in their view the evidence leans heavily in the other direction.

READ MORE: Donald Trump attacks social media firms after Facebook bans extremist figures 

“As former federal prosecutors, we recognise that prosecuting obstruction of justice cases is critical because unchecked obstruction — which allows intentional interference with criminal investigations to go unpunished — puts our whole system of justice at risk,” the letter says.

“We believe strongly that, but for the OLC memo, the overwhelming weight of professional judgment would come down in favour of prosecution for the conduct outlined in the Mueller report.”