Mueller, the former FBI director, is investigating Russian interference in the 2016 presidential election. He also is looking into whether Trump's campaign coordinated with Russians in that meddling, and whether the president personally obstructed justice in official inquiries into those questions.

One of Trump's lawyers, Jay Sekulow, said, "The President today answered written questions submitted by The Special Counsel's Office. The questions presented dealt with issues regarding the Russia-related topics of the inquiry. The President responded in writing."

Neither the questions from Mueller, nor the answers Trump gave the special counsel, were made public.

President Donald Trump has submitted answers to written questions posed to him by special counsel Robert Mueller's office, Trump's legal team announced Tuesday.

Rudy Giuliani, another lawyer for Trump, said, "It has been our position from the outset that much of what has been asked raised serious constitutional issues and was beyond the scope of a legitimate inquiry."

"This remains our position today," Giuliani said. "The President has nonetheless provided unprecedented cooperation. The Special Counsel has been provided with more than 30 witnesses, 1.4 million pages of material, and now the President's written responses to questions. It is time to bring this inquiry to a conclusion."

Earlier Tuesday, Trump had told reporters that his answers to Mueller were "all finished"

"The lawyers have them. The written answers to the witch hunt that's been going on forever," Trump said. "No collusion, no nothing. They've been finished. Finished them yesterday."

"The lawyers have them. I assume they'll turn them in today or soon," the president said.

Trump repeatedly has decried Mueller's probe.

Two weeks ago, he forced out his attorney general, Jeff Sessions, after long holding a grudge for Sessions' decision to recuse himself from any involvement in the investigation of Russian interference in the election.

Sessions' move in early 2017, which came as a result of his own contacts with Russians during the campaign, led several months later to the appointment of Mueller as special counsel.