Hillary Clinton was hit with new allegations of corruption after it was suggested one of her close aides tried to pressure the FBI to change the classification level of one of her emails while the agency was investigating her.

Patrick Kennedy, the US State Department Undersecretary for Management, was said to have contacted the FBI to ask for the change. There was then said to have been discussion of a "quid pro quo".

The FBI was investigating Mrs Clinton's use of a private email server while she was US Secretary of State. She was ultimately not criminally charged.

Republicans quickly seized on the new disclosure as evidence of collusion within the Obama administration to protect Mrs Clinton, now the Democratic presidential nominee.

Donald Trump, the Republican nominee, said the incident represented "corruption confirmed".