WASHINGTON: President Donald Trump attacked Special Counsel Robert Mueller on Monday, two days before the former FBI chief testifies in Congress -- the first time he will answer questions about his report on Russian election meddling and Trump's alleged obstruction.

Trump repeated his longstanding claim that Mueller's investigation was a biased "witch hunt" and falsely said that the special counsel's final report, released in April, found no collusion with Russia by Trump's 2016 campaign team and no obstruction of justice by the president.

"Highly conflicted Robert Mueller should not be given another bite at the apple. In the end it will be bad for him and the phony Democrats in Congress who have done nothing but waste time on this ridiculous Witch Hunt," Trump tweeted.

"Result of the Mueller Report, NO COLLUSION, NO OBSTRUCTION!"

Mueller will take questions from lawmakers for the first time on the Russia investigation when he appears before two separate Democratic-led House committees on Wednesday.

His 448-page report documents extensive contacts between the Trump campaign and Russians, including attempts to cooperate or collude, neither of which is a specific crime.

But Mueller ruled in the end that there was not enough evidence to recommend charges of criminal conspiracy, the main legal charge he could make use of.

The veteran prosecutor also laid out in detail 10 instances when Trump allegedly tried to obstruct the investigation.

But he said he was prevented from recommending charges against Trump because he was prohibited by Justice Department rules from lodging criminal charges against a sitting president.

How Mueller describes the obstruction allegations could make his testimony on live television Wednesday explosive.

"We want the American people to hear directly from Special Counsel Mueller on what his investigation found," Representative Jerry Nadler -- the chairman of the House Judiciary Committee, one of the two panels welcoming Mueller -- said Sunday.

"The report presents very substantial evidence that the president is guilty of high crimes and misdemeanors," he said, using the legal phrase that serves as the basis for impeachment. —AFP