The FBI has interviewed Hillary Clinton’s closest aides, including top adviser Huma Abedin, over the Democratic presidential front-runner’s use of a private email server to store sensitive government information, a source briefed on the matter told The Post.

Over the past few weeks, federal investigators have quizzed Abedin and the other aides as they try to build a case against Clinton to prove that she mishandled classified information while she was secretary of state from 2009 to 2013 during President Obama’s first term, the source said.

But the FBI has not yet been able to establish that Clinton “willfully” ran afoul of any laws, the source said.

“This is routine in an investigation like this,” the source said. “The FBI starts from the bottom and they go up the food chain.”

“They’ve interviewed almost everyone on her staff and Hillary is going to be the last in line because she’s the subject of the investigation. They want to have all their ducks in a row before they talk to her,” the source added.

The FBI is expected to interview Clinton in the coming weeks, according to the source.

The State Department’s inspector general and US intelligence agencies also are probing whether Clinton broke any rules or laws by using her private server for sensitive information.

Clinton’s server held nearly 2,200 emails that contained information now deemed classified — and 22 that were labeled “Top Secret.”

While on the campaign trail, Clinton has said that her use of the private email was an error.

But she has claimed that she never sent or received any sensitive records that were marked classified at the time.