Lawmakers have urged US President Donald Trump to supply investigators with any “tapes” of his conversations with sacked FBI director James Comey.

The president referenced alleged “tapes” in a tweet implying he may have records of conversations with Mr Comey, warning the former FBI director, who he abruptly fired last week, against leaking to the media.

“James Comey better hope that there are no ‘tapes’ of our conversations before he starts leaking to the press,” Mr Trump tweeted on Saturday (AEST).

The White House has declined to confirm whether or not the alleged “tapes” exist.

Republican Senator Lindsey Graham said in an NBC interview the White House should “clear the air” about whether there were any tapes.

“You can’t be cute about tapes. If there are any tapes of this conversation, they need to be turned over,” he said on the NBC’s Meet the Press programme.

Mr Graham also said Mr Trump should “back off” to allow an FBI investigation into possible Russian meddling in the 2016 US election to go forward – an investigation Mr Comey had headed up prior to his sacking.

“I have no evidence that the president colluded with the Russians at all,” Mr Graham said.

“Nobody on the campaign that I know of has colluded with the Russians. But we don’t know all of the evidence yet.”

Similarly, Republican Senator Mike Lee told Fox News it was “inevitable” members of the Trump administration would be subpoenaed if such “tapes” did exist and the White House would be required by law to release the recordings.

Mr Lee added that recording conversations in the White House was “not necessarily the best idea”.

Mr Trump’s threat regarding tapes has escalated calls for an independent probe into the alleged Russian meddling in the 2016 US election.

Senate Democratic Leader Chuck Schumer said if there were any tapes, Mr Trump should supply them to Congress and warned that the destruction of any such tapes would be illegal.

He said he supported a call for an independent prosecutor to oversee the investigation.

“To have that special prosecutor, people would breathe a sigh of relief because then there would be a real independent person overlooking the FBI director,” Mr Schumer told CNN’s State of the Union.

But Republican leaders in the Senate maintain that such a change would interfere with Congress’ ongoing investigations.

“Right now, it is a counterintelligence investigation, not a criminal investigation. So you don’t need a special prosecutor,” Mr Graham said.

The Justice Department began interviewing candidates to replace Mr Comey as FBI director this weekend.