WASHINGTON • Around 150 more of the e-mails that former United States secretary of state Hillary Clinton kept on a private server have been retroactively deemed as classified, the US State Department said, as it released over 4,000 more of the e-mails.

Mrs Clinton has been criticised for using a private server rather than an official government domain for all her e-mails during her time at the State Department.

Reporters and Mrs Clinton's 2016 presidential campaign rivals immediately began scouring the 7,000 additional pages of e-mails after their release on Monday.

Perhaps the greatest danger to her, with no smoking gun emerging immediately, lay in the e-mails that officials said had now seen their security status upgraded to "classified" or above, implying they should not have been sent.

State Department spokesman Mark Toner said that the process of re-evaluating the remaining unreleased e-mails was continuing.

Last month, officials said that 63 other e-mails had also been "upgraded in some form".

Critics allege that she used a server physically located in the bathroom of a private Internet provider to avoid political scrutiny of her time as the top US diplomat.

They also say that she put national security at risk by taking classified data out of supposedly secure government systems and putting it onto an unauthorised network that could be prey to hackers.

Mrs Clinton insists none of the e-mails on the private server were formally marked "classified" nor any higher designation like "top secret". If the probe reveals that classified or secret information was shared on unsecured networks or with individuals without a security clearance, she or her staff could face legal consequences.

All of Mrs Clinton's official correspondence is scheduled to be released by next January.

AGENCE FRANCE-PRESSE