Washington: US President Donald Trump asked the FBI director, James Comey, to shut down the federal investigation into Mr Trump's former national security adviser, Michael Flynn, in an Oval Office meeting in February, according to a memo that Mr Comey wrote shortly after the meeting.

"I hope you can let this go," the president told Mr Comey, according to the memo.

The existence of Mr Trump's request is the clearest evidence that the president has tried to directly influence the Justice Department and FBI investigation into links between Mr Trump's associates and Russia.

Mr Comey wrote the memo detailing his conversation with the president immediately after the meeting, which took place the day after Mr Flynn resigned, according to two people who read the memo.