A congressional committee has requested all FBI notes of meetings between Trump and Comey
Donald Trump is facing fresh controversy after US media reported that he urged the then FBI director James Comey to end an investigation into former national security adviser Michael Flynn.
The story was first reported in the New York Times, in a story detailing an apparent memo written by Mr Comey after a meeting in the Oval Office in February.
The story was later reported by other US media outlets, including CNN.
According to the reports, Mr Trump told Mr Comey: "I hope you can let this go."
Michael Flynn resigned from his position in February, amid claims he misled the administration about his contacts with Russia.
The FBI, meanwhile, has been carrying out an investigation into alleged links between the Trump campaign and Russia.
Last night, Republican Jason Chaffetz - chair of the House Oversight Committee - wrote a letter to the acting director of the FBI asking for all notes and recordings relating to communications between Mr Comey and Mr Trump.
Referring to the the latest reports, Mr Chaffetz wrote: "If true, these memoranda raise questions as to whether the President attempted to influence or impede the FBI's investigation as it relates to Lt Gen Flynn."
In a statement, the White House moved to deny the reports, saying: "The president has never asked Mr Comey or anyone else to end any investigation, including any investigation involving General Flynn.
"This is not a truthful or accurate portrayal of the conversation between the president and Mr Comey.”
Speaking in the Senate after the latest report, Senate minority leader Chuck Schumer said: "I was shaken by the report in the New York Times that alleged that the president tried to shut down an active FBI investigation into a close political associate.
"The country is being tested in unprecedented ways," he argued. "I say to all my colleagues in the Senate: history is watching."
The latest development comes only a week after Mr Trump dismissed Mr Comey.
Although the administration initially cited Comey's handling of the Hillary Clinton email scandal as the reason behind the firing, Trump later acknowledged that 'this Russia thing' was on his mind when he made the decision.
"[Comey is] a showboat and a grandstander," Mr Trump claimed in an interview with NBC News.
It is the second controversy in as many days for the US President, following the Washington Post report that he gave classified information to the Russian foreign minister and ambassador during a White House meeting last week.