WASHINGTON (REUTERS) - US Special Counsel Robert Mueller will not testify before Congress next week, House Judiciary Committee Chairman Jerrold Nadler said on Friday (May 10).

Nadler told reporters that he hopes not to have to subpoena Mueller to appear before lawmakers, but that he would do so if necessary. He declined to characterise ongoing negotiations between his committee, Mueller and the Justice Department.

"We're talking to the Department of Justice. We're talking to Mueller. Hopefully he will come in. It won't be next week," the New York Democrat said.

"He will come at some point. If necessary, we will subpoena him and he will come."

The House Judiciary committee has never set a date for Mueller to testify, but members have spoken tentatively about May 15.

Nadler reiterated plans to hold former White House counsel Don McGahn in contempt if he does not appear before the committee to testify on May 21 under an existing subpoena.

"He knows that if he doesn't testify on the 21st without a court order, which he won't get, he'll be subject to a contempt citation," the chairman said.

The White House earlier this week had directed McGahn not to comply with an earlier summons.

Mueller's potential testimony comes as House Democrats seek to further their investigations following the release of Mueller's report on his two-year-plus investigation into Russian interference into the 2016 US presidential election and potential obstruction by US President Donald Trump and his campaign.

Mueller's team of prosecutors detailed extensive contacts between Trump's campaign and Moscow but concluded there was insufficient evidence to show a criminal conspiracy between Russia and the campaign.

They also outlined 11 instances in which the president tried to impede the special counsel's investigation, but avoided a conclusion on whether or not Trump obstructed justice.