Hillary Clinton has given in to months of demands that she relinquish the personal email server she used while she was US secretary of state.
Mrs Clinton has directed that the device be given to the Justice Department.
The decision advances the investigation into the Democratic presidential front-runner’s use of a private email account as the nation’s top diplomat and whether secret information was sent improperly via and stored on the home-brew server she ran from her house in suburban New York City.
Clinton campaign spokesman Nick Merrill said she had “pledged to co-operate with the government’s security inquiry, and if there are more questions, we will continue to address them”.
It is not clear if the device will yield any information. Mrs Clinton’s lawyer said in March that no emails from the main personal address she used while secretary of state still “reside on the server or on back-up systems associated with the server”.
Until now Mrs Clinton refused demands from Republican critics to turn over the server to a third party, with lawyer David Kendall telling the House of Representatives committee investigating the deadly 2012 attacks that killed four Americans in Benghazi, Libya, that “there is no basis to support the proposed third-party review of the server”.
Republicans jumped on the decision to change course, as well as the additional disclosure that two emails that traversed Mrs Clinton’s personal system were subsequently given one of the government’s highest classification ratings.
“All this means is that Hillary Clinton, in the face of FBI scrutiny, has decided she has run out of options,” Republican National Committee chairman Reince Priebus said. “She knows she did something wrong and has run out of ways to cover it up.”
Federal investigators have begun looking into the security of Mrs Clintons’ email set-up amid concerns from the inspector general for the intelligence community that classified information may have passed through the system.
There is no evidence she used encryption to shield the emails or her personal server from foreign intelligence services or other potentially prying eyes. Mr Kendall has said previously that Mrs Clinton is “actively co-operating” with the FBI inquiry.
In March Mrs Clinton said she exchanged about 60,000 emails in her four years in Barack Obama’s administration, about half of which were personal and were discarded. She turned over the other half to the State Department last December.
The department is reviewing those emails and has begun the process of releasing them to the public.
“As she has said, it is her hope that state and the other agencies involved in the review process will sort out as quickly as possible which emails are appropriate to release to the public, and that the release will be as timely and transparent as possible,” Mr Merrill said.
Meanwhile Mr Kendall gave the Justice Department three thumb drives containing copies of work-related emails sent to and from Mrs Clinton’s personal email addresses via her private server.
He gave the thumb drives, containing copies of about 30,000 emails, to the FBI after the agency determined he could not remain in possession of the classified information contained in some of the emails, according to a US official briefed on the matter.
The State Department previously said it was comfortable with Mr Kendall keeping the emails at his Washington office.
Word that Mrs Clinton had relented on giving up possession of the server came as Republican sentor Chuck Grassley of Iowa said two emails that traversed Mrs Clinton’s personal system were deemed “Top Secret, Sensitive Compartmented Information” – a rating that is among the government’s highest classifications.
Mr Grassley said the inspector general of the nation’s intelligence community had reported the new details about the higher classification to Congress on Tuesday.
Those two emails were among four that had previously been determined by the inspector general of the intelligence community to have been secret at the time they were sent. The State Department disputes that the emails were classified at that time.
The inspector general for the intelligence community had told Congress that potentially hundreds of classified emails are among the cache that Mrs Clinton provided to department.
Mrs Clinton has defended her use of the server, saying she used it as a matter of convenience to limit the number of electronic devices she had to carry.