AN OLD friend of former secretary of state Hillary Clinton played a major role in advising her on US politics and even her dealings with President Barack Obama's White House despite holding no formal government position.

The State Department has released emails that showed adviser Sid Blumenthal sent Mrs Clinton exhaustive memos on domestic issues, taking a more active role in advising her than was previously known.

He urged her to speak out against Tea Party conservatives and encouraged her to get the White House to "rein in" a key Obama aide who had upset him,

Her close links to Mr Blumenthal, a former aide to President Bill Clinton, could rebound on the former first lady as she runs for the Democratic nomination for the November 2016 presidential election.

She is under pressure for using a private email account instead of a government one when she served as America's top diplomat from 2009-2013. Political opponents accuse her of sidestepping laws on transparency and record-keeping.

Under orders from a judge, the State Department released a new batch of 7,000 pages of Clinton emails from that period, casting some light on how she handled her job.

Mr Blumenthal wrote frequently with forthright opinions both on foreign policy issues like the Middle East but also about US politics as the 2010 mid-term elections approached.