WASHINGTON (BLOOMBERG) - President Donald Trump defended his former national security adviser Michael Flynn three days after demanding his resignation, saying the retired army general did nothing wrong.

Mr Trump said at a news conference on Thursday (Feb 16) that Mr Flynn "was just doing his job" in a conversation he had with the Russian ambassador to the US Sergey Kislyak.

Mr Flynn resigned on Monday amid revelations that he has misled administration officials, including Vice-President Mike Pence, over his contact with Russia.

"I fired him because of what he said to Mike Pence, very simple," the president said.

Mr Trump's decision to ask for Mr Flynn's resignation followed news reports that the aide had discussed sanctions levied against Russia in a conversation with Mr Kislyak, despite insisting he had not done so.

The revelations surrounding Mr Flynn - and an ensuing report from the New York Times that despite public denials, Trump campaign aides and associates had repeated contacts with Russian intelligence officials before his election - have prompted bipartisan calls for investigation, and thrown the fledgling White House into chaos.

"I think there needs to be fulsome investigation on all angles relative to nefarious activities that were taking place with Russia, beginning in March but even going back before that time," Senator Bob Corker, a Tennessee Republican and chairman of the Foreign Affairs Committee, told reporters on Tuesday.

The controversy intensified when the New York Times reported late Tuesday that Mr Trump campaign aides and associates "had repeated contacts with senior Russian intelligence officials in the year before" the November 2016 election, citing four current and former US officials the newspaper didn't identify.

The Times reported that there's been no evidence uncovered that Mr Trump's campaign colluded with Russian attempts to influence the election. White House press secretary Sean Spicer has said he is not aware of any such instances of pre-election contact.