US spies drew up a dossier on gay Conservative minister Alan Duncan, leaked documents show.
Mr Duncan, now the international development minister, was apparently of special interest to the US and is the only British MP to have been singled out so far.
He was shadow pensions minister at the time the document was written in January 2010.
The communication was one of three million released by the website Wikileaks.
The cable, sent on January 22nd, was signed off by Elizabeth Pitterle, head of intelligence operations.
She thanked the US embassy in London for gathering intelligence on Mr Duncan’s “friendship with … William Hague”, saying it was “particularly insightful and exceptionally well timed, as analysts are preparing finished products on the Conservative leadership for senior policy-makers”.
The cable asked for more information on “Duncan’s relationship with Conservative party leader David Cameron and William Hague”, and asked:”What role would Duncan play if the Conservatives form a government? What are Duncan’s political ambitions?”
Mr Duncan was the first Tory MP to come out and is in a civil partnership. He once shared a flat with Mr Hague, who denied he was gay this summer after rumours spread about his sexuality and his sharing a hotel room with a male aide.
In September, Mr Duncan defended Mr Hague against media interest in his personal life, telling journalists to “back off”.