Hillary Clinton's campaign had its network hacked as part of a broader cyber attack on Democratic political organisations, according to US media.

The latest attack follows reports of two other hacks on the Democratic National Committee (DNC) and the party's fundraising Democratic Congressional Campaign Committee (DCCC).

A spokesman from the Clinton campaign said in a statement on Friday that an analytics data program maintained by the DNC and used by the campaign and other organisations "was accessed as part of the DNC hack".

Clinton campaign spokesman Nick Merrill said: "Our campaign computer system has been under review by outside cyber security experts. To date, they have found no evidence that our internal systems have been compromised."

The national security division of the Department of Justice is looking into whether cyber attacks on Democratic political organisations threatened US security, according to US media.

Cyber security experts and US officials had said earlier this week that they had concluded, based on analysis of the DNC hack, that Russia engineered the release of Democratic Party emails to influence the presidential election.

The FBI said on Friday that it was "aware of media reporting on cyber intrusions involving multiple political entities, and is working to determine the accuracy, nature and scope of these matters."

"The FBI takes seriously any allegations of intrusions, and we will continue to hold accountable those who pose a threat in cyberspace," the agency said.

It is not immediately clear what Clinton campaign information could have been accessed, or how the "analytics data program" was used.