The US State Department has said it would review Hillary Clinton's request to have emails sent from her private email address published.

"I want the public to see my email. I asked State to release them. They (the State Department) said they will review them for release as soon as possible," Clinton said in a tweet late on Wednesday night.

Marie Harf, the deputy spokesperson at the State Department, said on Thursday that the review would take some time "given the sheer volume of the document set".

Clinton, a leading Democrat contender likely to enter the 2016 presidential race, faced criticism this week when it emerged that she exclusively used a private email account for her work while serving as the US top diplomat from 2009 to 2013.

The revelations opened a potential legal quagmire, with accusations that she violated federal record-keeping rules.

But it also raised questions about what might have motivated Clinton to not use a federal government email account making her correspondence part of the public record, and prompted critics to argue the presumptive Democratic White House frontrunner was seeking to evade scrutiny.

'We're going to get them'

Earlier Wednesday, Trey Gowdy, the Republican chairman a special House committee set up to investigate the deadly terror attacks on the US mission in Benghazi said he would take "legal recourse" to obtain all emails the presumed Democratic frontrunner wrote while being the secretary of state.

Later in the day, the committee issued subpoenas "for all communications of former secretary of state Hillary Clinton related to Libya," Jamal Ware, the committee spokesman, said in a statement.

The committee also sent "preservation letters" to Internet firms, demanding they protect all relevant documents.

"We're going to get them," committee chairman Gowdy told reporters of the emails. "We have to go to the source, which would be secretary Clinton herself."

Clinton had no federal government email address during her four years at the State Department, and aides did not seek to preserve her emails on department servers at the time, according to The New York Times, which first reported the story.

Source: AFP