WASHINGTON — US special counsel Robert Mueller has submitted a confidential report to Attorney General William Barr, marking the end of his nearly two-year investigation into Russian interference in the 2016 election, media reported Friday.

The Justice Department notified Congress late Friday that it had received Mueller's report but did not describe its contents, according to The Washington Post.

No details of Mueller's findings have been released. It is not clear how soon they will be made public.

Barr reportedly said he could brief Congress as early as this weekend about the findings.

The Mueller-led inquiry focused on possible collusion between the Trump campaign and Moscow during the 2016 presidential election and whether the president obstructed justice.

The White House said in a statement Friday that it has not received or been briefed on the special counsel's report.

"The next steps are up to Attorney General Barr, and we look forward to the process taking its course," the statement added.

Mueller, who was appointed by Deputy Attorney General Rod Rosenstein in May 2017, is required to submit a report to Barr at the conclusion of his investigation. Barr, in turn, is required to notify Congress about Mueller's findings.

According to special counsel regulations, the report must explain Mueller's "prosecution or declination decisions." Barr has said he will write his own report summarizing Mueller's findings.

The probe, which has shadowed Trump's presidency, has led to felony charges against 34 people, including six Trump associates, and three companies.

Trump has repeatedly dismissed any collusion between his campaign and Moscow, while slamming the wide-ranging inquiry as a "hoax" or "witch hunt." Russia has denied any meddling in the 2016 presidential election.