Donald Trump would consider pardoning Paul Manafort if his ex-campaign manager is convicted over Russian meddling in the 2016 election. Picture: AP Photo/Alex Brandon

New York - Donald Trump would consider pardoning Paul Manafort if his ex-campaign manager is convicted over Russian meddling in the 2016 election, the US president told the New York Post on Wednesday.

Manafort had reached a plea agreement to cooperate with Robert Mueller's investigation, but on Monday the special counsel's office alleged Manafort had violated the deal by lying to federal investigators.

A pardon was "not off the table," Trump told the Post.

"It was never discussed, but I wouldn't take it off the table. Why would I take it off the table?" the president added in the Oval Office interview.

Trump alleged that Mueller had asked Manafort and others to lie.

"If you told the truth, you go to jail. You know this flipping stuff is terrible. You flip and you lie and you get - the prosecutors will tell you 99 per cent of the time they can get people to flip. It's rare that they can't," Trump said.

Manafort, who headed Trump's campaign for two months in mid-2016, pleaded guilty in September to conspiring to defraud the US and conspiring to obstruct justice.

The charges, though not directly linked to Mueller's main investigation, were seen as part of a strategy to pressure Manafort to cooperate in the probe into the Trump campaign's possible collusion with Russia and possible attempts to obstruct efforts to uncover it.

The New York Times reported on Tuesday that the 69-year-old's lawyer was briefing Trump's legal team on the evidence he had given Mueller.

dpa