White House spokesman Josh Earnest described as being mistake the use of personal email in work-related matters by Secretary of Defense Ash Carter.

The US administration will not take any procedures against Carter, he added.

Some officials of the White House have asked the Pentagon last May about the reasons behind Carter's use of his personal email to conduct some work matters, according to the spokesman.

Carter said all files saved in his personal email are safe, Earnest asserted.

Carter said the "mistake" was entirely his, telling reporters in Iraq that he had used an iPhone to send administrative emails and stopped doing so a few months ago.

Carter took up the post of defense secretary in February — a month before the Clinton email controversy exploded.

Clinton's use of private, nongovernmental email account during her time as secretary of state has dogged the current presidential candidate's campaign. President Barack Obama recently called it a mistake but said the issue had been "ginned up" by the campaign season.

Sources: MENA