Michael Flynn, Donald Trump's national security adviser, has resigned from his post after less than one month in office following reports that he had misled Vice-President Mike Pence about his contacts with Russia.

The resignation capped a day of mixed messages from the White House. Kellyanne Conway, senior counsellor to the president, had earlier said Mr Trump had "full confidence" in Mr Flynn, before it emerged the president was "evaluating" the adviser's position.

Mr Flynn's contact with Russia has been described as "potentially illegal" due to the 1799 Logan Act, which bans private US citizens from negotiating with countries with which the US is in dispute.