The Obama administration has discovered a further chain of emails that Hillary Clinton failed to disclose when giving over a supposed full record of work related correspondence during her time as Secretary of State.
The Democrat front runner came under fire earlier this year for using a private email account when in government office. She has since stated she has handed over the entirety of her work emails.
The messages uncovered today were exchanged between Mrs Clinton and General David Petraeus, when he headed the US military’s Central Command, in charge of running the wars in Iraq and Afghanistan.
They began before Mrs Clinton started as Secretary of State and continued into her early days in the role.
Officials have stated the emails are largely personal, however it calls into question Mrs Clinton’s claim on the CBS television network this week that “we provided all of them”, when asked whether she had disclosed the messages from her private account.
The FBI and several congressional committees are investigating.
A State Department spokesman James Kirby the agency will incorporate the newly discovered emails into a review of record retention practices that Clinton's successor, John Kerry, has intiated.
He added: “We have also informed Congress of this matter.”
These steps are unlikely to satisfy Mrs Clinton’s critics from the Republican party.
A House committee plans to hold a public hearing with Mrs Clinton next month about what her emails might reveal about the attack on a US diplomatic outpost in Libya that killed four Americans in 2012.
The Senate Judiciary Committee's Republican chairman said this week he wants the Justice Department to tell him if a criminal investigation is under way into Mrs Clinton's use of private emails.
The favourite for the Democrat party’s Presidential nomination has continually denied wrongdoing.
Earlier this week Mrs Clinton said: "When I did it, it was allowed, it was above board.
“And now I'm being as transparent as possible, more than anybody else ever has been.”
Brian Fallon, the Clinton campaign's press secretary, wrote on Twitter earlier today: "We always said the emails given to State dated back only to March 09. That was when she started using http://clintonemail.com."Reuse content