FBI Director James Comey has been fired from his position by US President Donald Trump.
The move came after the FBI was forced to send a letter to Congress to clarify mistatements by Comey during a Senate Judiciary Committee hearing.
A statement from the White House said that Trump had informed Comey "that he has been terminated and removed from office."
"President Trump acted based on the clear recommendations of both Deputy Attorney General Rod Rosenstein and Attorney General Jeff Sessions," the statement continued.
"The FBI is one of our nation's most cherished and respected institutions and today will mark a new beginning for our crown jewel of law enforcement," Trump said, according to the statement.
The search for the next director would start immediately, he added.
Senator Lindsey Graham, who sits on the panel investigating the alleged links between Russia and the Trump administration, said the removal of Comey was "a difficult decision for all concerned".
"Given the recent controversies surrounding the director, I believe a fresh start will serve the FBI and the nation well," he said.
It was not immediately clear why Comey was fired but earlier in the day reports had suggested that he had mistated facts about Hillary Clinton's aide Huma Abedin and her handling of sensitive emails.
Comey came under fire in the last days of the presidential campaign when he sent a letter to Congress informing it of further investigations into Clinton's private email server.
That announcement was made just 10 days before the election took place – an event that many, including Clinton, claimed contributed to her defeat.
In Trump's dismissal letter to Comey, Trump wrote: "While I greatly appreciate you informing me, on three separate occasions, that I am not under investigation, I nevertheless concur with the Department of Justice that you are not able to effectively lead the bureau."
A number of people have questioned the timing of the firing and suggested it was because Comey was a key player in investigating alleged Russian collusion with members of Trump's administration during the 2016 presidential election.
Senate Democratic Leader Chuck Schumer said he told President Trump he was making a "big mistake" in firing Comey. The senator said that the investigation into Russia's meddling in the 2016 election should be "as far away as possible" from the White House.
Congressman Elijah Cummings, ranking member of the house committee on oversight and government reform, has called for "immediate emergency hearings" on Comey's termination.
"Congress needs to have immediate emergency hearings to obtain testimony directly from Attorney General Sessions, the deputy attorney general, and FBI Director Comey," Cummings said in a statement.
"The White House was already covering up for Michael Flynn by refusing to provide a single document to Congress, and now the President fired the one independent person who was doing the most to investigate President Trump and his campaign over allegations of coordination with Russia.
"It is mindboggling that the Attorney General – who claimed to have recused himself – was directly involved in the decision to fire Director Comey according to the White House itself. There is now a crisis of confidence at the Justice Department, and President Trump is not being held accountable because House Republicans refuse to work with us to do our job.
"Congress must restore credibility, accountability, and transparency to this investigation and finally pass legislation to create a truly independent commission," said Cummings.