WASHINGTON • US President Donald Trump yesterday said his former national security adviser Michael Flynn should seek immunity from prosecution, and called probes into alleged contacts between his administration and the Russian government a political "witch hunt".

"Mike Flynn should ask for immunity in that this is a witch hunt (excuse for big election loss), by media & Dems, of historic proportion!" said Mr Trump in a Twitter post, using the abbreviation for Democrats.

While it is unclear if Mr Trump was coordinating with his former adviser, Mr Flynn, a retired general, has told investigators that he is willing to be interviewed in return for immunity from prosecution.

The Wall Street Journal reported that Mr Flynn made the offer to the Federal Bureau of Investigation and two congressional committees.

"General Flynn certainly has a story to tell, and he very much wants to tell it, should the circumstances permit," said Mr Robert Kelner, Mr Flynn's lawyer, in a statement late on Thursday.

He added: "We will not comment right now on the details of discussions between counsel for General Flynn and the House and Senate Intelligence Committees, other than to confirm that those discussions have taken place."

Mr Flynn's lawyer also suggested immunity is justified, because Mr Flynn was "the target of unsubstantiated public demands by members of Congress and other political critics that he be criminally investigated".

Mr Kelner, a partner at law firm Covington and Burling in Washington, said: "No reasonable person, who has the benefit of advice from counsel, would submit to questioning in such a highly politicised, witch hunt environment without assurances against unfair prosecution."

The Wall Street Journal said it was not clear what exactly Mr Flynn offered to discuss, but it quoted one unnamed official as saying that the retired army general's bid for immunity suggested potential "legal jeopardy" for him.

The New York Times quoted a congressional official as saying that investigators are wary of cutting a deal with Mr Flynn until they are further along in their probe and have a better idea of what information he might offer.

Mr Flynn was forced out of the Trump administration after it was revealed that he had misled Vice-President Mike Pence about his contacts with the Russian ambassador to the US after Mr Trump's victory.

BLOOMBERG, REUTERS, AGENCE FRANCE-PRESSE