The incoming Democratic chairman of the House Judiciary Committee has said it would be an “impeachable offence” if it was proved that US President Donald Trump had directed illegal hush money payments to women.

Representative Jerry Nadler described the details in prosecutors’ filings on Friday in the case of Mr Trump’s former personal lawyer, Michael Cohen, as evidence that the president was “at the centre of a massive fraud”.

Prosecutors for the first time link Mr Trump to a federal crime of illegal payments to buy the silence of two women during the 2016 campaign, and lay out previously undisclosed contacts with Russians during the 2016 election.

Mr Nadler stressed the need for continuing investigations and a deeper look by Congress into the extent of presidential misconduct.

Trump Russia Probe Lies
The Justice Department said Mr Trump told Cohen, pictured, to make illegal payments to two women (Julie Jacobson/PA)

“They would be impeachable offences,” Mr Nadler said of the illegal payments.

“Whether they are important enough to justify an impeachment is a different question, but certainly they’d be impeachable offences because even though they were committed before the president became president, they were committed in the service of fraudulently obtaining the office.”

Mr Nadler said it was too early to say whether Congress would pursue impeachment proceedings based on the illegal payments alone.

Lawmakers would need to weigh the gravity of the offence to justify “overturning” the result of the 2016 election, he said.

He and other lawmakers said they would need to await findings from special counsel Robert Mueller’s investigation into Russian election interference and possible co-ordination with the Trump campaign.

Mr Mueller has not said when he will complete a report of any findings and it is not clear that any such report would be made available to Congress. That would be up to the attorney general.

Mr Trump said on Friday that he would nominate former attorney general William Barr to the post.

Mr Nadler indicated that Democrats, who will control the House in January, will step up their own investigations into possible collaboration between the Trump campaign and Russia.

He said Congress, the Justice Department and the special counsel needed to dig deeper into the allegations, which included questions about whether Mr Trump lied about his business arrangements with Russians and about possible obstruction of justice.

“The new Congress will not try to shield the president,” he said.

“We will try to get to the bottom of this, in order to serve the American people and to stop this massive conspiracy — this massive fraud on the American people.”

Jerry Nadler
Jerry Nadler is the incoming chairman of the Judiciary panel (AP Photo/J. Scott Applewhite)

In legal filings on Friday, the Justice Department stopped short of accusing Mr Trump of directly committing a crime. But it said Mr Trump told Cohen to make illegal payments to porn actress Stormy Daniels and former Playboy model Karen McDougal, both of whom claimed to have had affairs with Mr Trump more than a decade ago and who threatened his White House bid.

Mr Trump has denied any wrongdoing.

In separate filings, Mr Mueller’s team also laid out evidence of additional contacts between Mr Trump’s associates and Russian intermediaries.

They detail how Cohen spoke to a Russian who “claimed to be a ‘trusted person’ in the Russian Federation who could offer the campaign ‘political synergy’ and ‘synergy on a government level'”.

Cohen said he never followed up on that meeting.