The US State Department is to restart its investigation into Hillary Clinton's handling of classified material when secretary of state.

The likely Democratic presidential nominee learned this week that she will not face criminal charges over her use of private email.

The FBI said that although she had sent and received sensitive material there was no evidence of intent.

Now that inquiry is over, the State Department will reopen its review.

As well as the former secretary of state, it will also include some of her former aides, all of whom have now left the department.

A spokesman for the department, John Kirby, said: "We will aim to be as expeditious as possible, but we will not put artificial deadlines on the process."

Former officials can still face "administrative sanctions," he said.

That could range from counselling and warnings to the revocation of security clearances.

Republican critics of the FBI decision not to recommend Clinton be prosecuted said this showed that she was above the law.

But FBI Director James Comey defended himself in front of a House committee on Thursday, reiterating that no reasonable prosecutor would recommend charges.

Clinton, who will be officially made her party's nominee later this month, was secretary of state until early 2013.