James Comey, the former FBI director who was fired this week by U.S. President Donald Trump, declined an invitation from the Senate Intelligence Committee to testify on the matter on May 16 after Trump warned him against speaking out.

The committee, which is in the midst of an investigation into Russian interference in the 2016 election, had hoped to hear from Comey in closed session. Comey oversaw the FBI's investigation of alleged Russian meddling in the election.

"He is not going to be testifying on Tuesday, but it is our hope in the not too distant future, that we can find time for him to come in and talk to our committee," Senator Mark Warner, the top Democrat on the committee, told MSNBC on May 12.

Trump earlier in the day had issued a warning to Comey on Twitter about speaking out, saying "James Comey better hope that there are no 'tapes' of our conversations before he starts leaking to the press!"

The tweet ignited a furor in Washington as it suggested Trump not only was attempting to intimidate Comey but has been taping his phone calls and conversations.

Based on reporting by AP and Reuters