Robert Mueller: Former FBI head to oversee Trump-Russia investigation
Former FBI boss Robert Mueller has been named as a special prosecutor to oversee an investigation into allegations that Russia and Donald Trump's campaign team collaborated to influence the 2016 US election.
Mr Mueller, who led the FBI through the aftermath of the September 11th attacks before retiring in 2013, said in a brief statement: "I accept this responsibility and will discharge it to the best of my ability."
Mr Trump meanwhile maintained that "a thorough investigation will confirm what we already know - there was no collusion between my campaign and any foreign entity."
The appointment came amid a growing Democratic outcry for someone outside the Justice Department to handle the politically charged investigation.
The James Comey memo
On Tuesday, revelations emerged in the New York Times that Mr Trump had asked fired FBI Director James Comey to shut down an investigation into ousted national security adviser Michael Flynn, who was an adviser to the president's election campaign.
Mr Trump was alleged to have made the request during a meeting at the White House in February, details of which Mr Comey is reported to have kept a record of in a memo.
The White House denied the account.
The Republican Chairman of the House Oversight Committee, Jason Chaffetz, has given the FBI until 24 May to hand over all documents and recordings that detail communications between Mr Comey and the president.
Mr Flynn, a retired general, resigned a day before the 14 February meeting, after it emerged he misled US officials about his contacts with Russia.
The president fired Mr Comey last week, saying he did so based on his very public handling of the Hillary Clinton email probe and how it affected his leadership of the FBI.
The appointment of Mr Mueller comes during a tumultuous week in Washington. A day before the New York Times' explosive report, the Washington Post claimed that the president shared highly classified information with Russian officials about Islamic State militants.
White House officials initially denied the report, then claimed that Mr Trump didn't even know the source of the information himself.
The president later took to Twitter to defend his "absolute right" to open dialogue with the Kremlin.
The Justice Department said Mr Mueller has resigned from his job at private law firm WilmerHale to take the job of special counsel.
It declined to explain the decision-making involved in the appointment.