(Recasts with Comey memo)
By Mark Hosenball and Susan Heavey
WASHINGTON, May 16 (Reuters) - U.S. President Donald Trump asked then-FBI Director James Comey to end the agency's investigation into ties between former White House national security adviser Michael Flynn and Russia, according to a source who has seen a memo written by Comey.
The explosive new development on Tuesday followed a week of tumult at the White House after Trump fired Comey and then discussed sensitive national security information about Islamic State with Russian Foreign Minister Sergei Lavrov.
The Comey memo, first reported by the New York Times, is likely to raise questions about whether Trump tried to interfere with a federal investigation.
Comey wrote the memo after he met in the Oval Office with Trump, the day after the president fired Flynn on Feb. 14 for misleading Vice President Mike Pence about the extent of his conversations last year with Russia's ambassador, Sergei Kislyak.
“I hope you can let this go,” Trump told Comey, according to a source familiar with the contents of the memo.
The New York Times said that during the Oval Office meeting, Trump condemned a series of government leaks to the news media and said the FBI director should consider prosecuting reporters for publishing classified information.
The White House denied the report in a statement, saying it was "not a truthful or accurate portrayal of the conversation between the President and Mr. Comey."
Flynn's resignation came hours after it was reported that the Justice Department had warned the White House weeks earlier that Flynn could be vulnerable to blackmail for contacts with Kislyak before Trump took office on Jan. 20.
Kislyak was with Lavrov at the White House last week when Trump disclosed the sensitive information.
A spokeswoman for the FBI declined to comment on the details of the memo.
The new development came as Republican and Democratic lawmakers pressured Trump to give a fuller explanation for why he revealed sensitive intelligence information to Lavrov.
The information had been supplied by a U.S. ally in the fight against the Islamic State militant group, the officials said.
(Additional reporting by Steve Holland, Amanda Becker, Doina Chiacu, Tim Ahmann, and Mark Hosenball in Washington and Ari Rabinovitch in Jerusalem; Writing by Alistair Bell; Editing by Frances Kerry and Peter Cooney)