The report was handed in moments ago, adding it was submitted to Attorney General William Barr. Details of the report and its outcome are not yet known. President Trump has denied any involvement with Moscow.
The report was not immediately made public – Mr Barr will have to decide how much to disclose – and it was not known if Mr Mueller found criminal conduct by Mr Trump or his campaign, beyond the charges already brought against several aides.
Mr Barr said he may send Congress a summary of Mr Mueller’s findings as soon as this weekend.
Mr Mueller, a former FBI director, had been examining since 2017 whether President Trump’s campaign conspired with Moscow to try to influence the election and whether the Republican president later unlawfully tried to obstruct his investigation.
White House spokeswoman Sarah Sanders said Mr Trump has not been issued a copy of the report.
She said: “The next steps are up to Attorney General Barr, and we look forward to the process taking its course. “The White House has not received or been briefed on the Special Counsel’s report.”
The following is a letter sent form Mr Barr to the heads of the Senate and House of Representatives Judiciary committees.
“I write to notify you pursuant to 28 C.F.R. 600.9(a)(3) that Special Counsel Robert S. Mueller III has concluded his investigation of Russian interference in the 2016 election and related matters. In addition to this notification, the Special Counsel regulations require that I provide you with “a description and explanation of instances (if any) in which the Attorney General” or acting Attorney General “concluded that a proposed action by a Special Counsel was so inappropriate or unwarranted under established Departmental practices that it should not be pursued.” 28 C.F.R. 600.9(a)(3). There were no such instances during the Special Counsel’s investigation.
“The Special Counsel has submitted to me today a “confidential report explaining the prosecution or delineation decisions” he has reached, as required by 28 C.F.R. 600.8(c). I am reviewing the report and anticipate that I may be in a position to advise you of the Special Counsel’s principal conclusions as soon as this weekend.
“Separately, I intend to consult with Deputy Attorney General Rosenstein and Special Counsel Mueller to determine what other information from the report can be released to Congress and the public consistent with the law, including the Special Counsel regulations, and the Department’s long-standing practices and policies. I remain committed to as much transparency as possible, and I will keep you informed as to the status of my review. Finally, the Special Counsel regulations provide that “the Attorney General may determine that public release of” this notification “would be in the public interest.” I have so determined, and I will disclose this letter to the public after delivering it to you.”
Investigators appeared to be particularly interested in a lucrative business deal with Moscow that was cancelled around the time of his 2016 campaign to become President.
The project came about despite Mr Trump denying any links to Moscow, or Vladimir Putin.
Mr Trump had announced his presidential candidacy in June 2015.
The news comes after critic James Comey surprisingly revealed he is “not rooting” for the US President to be impeached should proof he colluded with Russia be found.
The former Director of the FBI insists he has “no idea” if the Mueller report into Russian meddling in Mr Trump’s winning presidential campaign will find anything, but hopes it will deliver the “fair administration of justice”.
Mr Comey, who was fired by Mr Trump in May 2017, states he is “morally unfit to be president of the United States” in a scathing assessment of his term in office.