US Secretary of State Hillary Clinton has been admitted to hospital in New York after the discovery of a blood clot. A spokesman says its linked to a concussion she suffered earlier this month after she fainted and had a fall at home. Officials say her condition is improving and have and have played down suggestions that it is anything more serious. Clinton has been out of the spotlight since mid-December and was forced to cancel a foreign trip. She was also due to testify in Congress over the deadly attack on the US embassy in Benghazi, Libya. Two of her aides appeared in her place. The 65-year-old is the most travelled secretary of state in history, having visited 112 countries. She’s due to step down in January and is widely tipped to run for the White House in 2016.