It notified the House Judiciary panel on Wednesday that it would refuse to comply with sweeping requests for documents and witness testimony while declaring that the legislative branch had no right to a "do-over" of the special counsel's Russia probe.

White House counsel Pat Cipollone sent a 12-page letter to the committee chairman, Democrat Jerrold Nadler, labelling congressional investigations as efforts to "harass" Trump in the wake of special counsel Robert Mueller's probe into Russian election interference.

Current and former administration officials will not be permitted to testify, according to the White House, and the administration will fight subpoenas as Congress moves to step up investigations into Trump's presidency and finances.

The White House counsel stopped short of invoking blanket executive privilege, and it will only cooperate with narrow requests from Nadler if Congress explained the legislative purposes behind them.

Nadler said the White House's arguments were "ridiculous" and would hold the president above the law.

He added, for the first time, that the committee was seriously considering "very large" fines for witnesses who do not comply.

"This flies in the face of the American idea that no one is above the law, and I reject it," Nadler said.

White House officials said the release of a redacted version of Mueller's 448-page report last month made the congressional probes unnecessary and gratuitous.

Though Trump and his allies routinely attacked Mueller's integrity, the White House has found fit to praise the special counsel when it suits them: Officials on Wednesday declared Mueller's team to be "professional" and "hard-charging" and insisted that Mueller's conclusions be honoured.

Mueller did not conclude that the Trump campaign conspired with Russia. He did not rule on whether Trump obstructed justice, although Attorney-General William Barr said the report shows that the president did not.

Cipollone stressed that the Mueller probe was "exhaustive," involving 2800 subpoenas, 500 executed search warrants and 500 witness interviews.

"The appropriate course is for the Committee to discontinue the inquiry," the White House counsel wrote. "Unfortunately, it appears that you have already decided to press ahead with a duplicative investigation, including by issuing subpoenas, to replough the same ground the Special Counsel has already covered."

Democrats are clashing with the administration on myriad fronts, including over access to Mueller's full report.

Trump for the first time earlier this month invoked the principle of executive privilege, claiming the right to block lawmakers from the unredacted document about Russian interference to help Trump in the 2016 election.

The Judiciary panel voted to hold Barr in contempt of Congress after he defied the committee's subpoena for the unredacted report.

Australian Associated Press