Hillary Clinton questioned by FBI on emails

US presidential candidate Hillary Clinton has been questioned by the FBI over her use of emails while she was secretary of state, her campaign says.

A spokesperson said it was a voluntary interview.

The FBI is investigating Clinton and her aides over whether they mishandled classified information on a private email server she used while serving as secretary of state.

Clinton denies handling classified information in her private emails.

She said she set up the email address for reasons of convenience, because it was easier to do everything from her Blackberry than to have several phones or tablets.

However, a state department inquiry accused her and other former US secretaries of state of poorly managing email security.

The justice department is now seeking to establish whether this constitutes a criminal offence.

On Friday, the US Attorney General Loretta Lynch said she would accept the findings of the FBI and prosecutors, when deciding whether to charge Clinton.

The day before, it was revealed that Lynch had met the former president, Clinton's husband Bill, in what she described as a "social" meeting but which she admitted would "cast a shadow" over the way her role in the case would be perceived.

Clinton is the presumptive nominee for the Democratic Party and party members are expected to confirm the nomination at a convention at the end of July.

Shortly before being sworn in as secretary of state in 2009, Hillary Clinton set up an email server at her home. She relied on it for all her electronic correspondence during her four years in office.

Why is this controversial?

It was probably not against the law.

But sceptics say she did it to have total control over her correspondence, becoming the sole arbiter of what should and shouldn't be provided to the government, made public via freedom of information requests or turned over to interested parties, such as the congressional committee investigating an attack on the US consulate in Benghazi.

Critics have also expressed concern that the system made her emails more vulnerable to being hacked.

Have other politicians done this?

Yes. Clinton is far from alone. Others have sometimes relied on personal email for official business.

But unlike them, Clinton used her personal email address exclusively.