NEW YORK (NYTIMES) - President Donald Trump said Saturday (Dec 2) that he had fired Michael Flynn, his first national security adviser, because he lied not just to the vice president but also to the FBI.

The president has long asserted that he fired Flynn in February because Flynn had lied to Vice President Mike Pence over whether he talked with the Russian ambassador, Sergey Kislyak, about sanctions imposed on Russia by President Barack Obama.

By saying on Twitter on Saturday that Flynn's lies to the FBI had also contributed to his firing, some took that to mean that Trump was acknowledging that he had known in February that Flynn was untruthful with the bureau's agents.

Any such admission would be important in light of Trump's effort that month to persuade the bureau's director at the time, James Comey, to drop the investigation into Flynn.

But White House officials said Trump was merely acknowledging what had happened the day before: Flynn's guilty plea for lying to the FBI about his conversations with Kislyak.

While Trump's tweet Saturday raised questions about what he knew, he did not actually write it, according to two people briefed on the matter. It was composed by his top personal lawyer, John Dowd, who was in contact with Trump on Friday and Saturday, trying to calm him after Flynn's guilty plea.

Dowd apologised to White House officials for the tweet, saying he should have been more careful with his language in trying to parrot a statement released Friday by another Trump lawyer, Ty Cobb.

It is not clear that Trump was ever told that the FBI believed Flynn had lied in his interview with agents. Shortly after the acting attorney general, Sally Yates, told the White House counsel, Donald McGahn II, in January that Flynn might be compromised because he had misled the vice president, McGahn briefed Trump, according to two people familiar with the matter.

McGahn told Trump that it was his impression from Yates that the federal authorities were not pursuing a case against Flynn for lying to the FBI, according to one of the people. It is unclear whether the president understood this to mean that Flynn had been cleared.

In a tweet on Sunday, Trump also said he never asked Comey to stop investigating Flynn. "I never asked Comey to stop investigating Flynn. Just more Fake News covering another Comey lie!" Trump tweeted.