Lord West, the Abba singer, and an extramarital affair

A government minister was bizarely linked with one of the singers from the 1970s supergroup Abba last night.

Amid gathering rumours, Admiral Sir Alan West was forced to insist that his friendship with the Swedish singer, Anni-Frid Lyngstad, was "innocent".

But it was subsequently revealed that the married security minister had admitted to an infidelity "some years ago" during a routine vetting procedure.

The revelations about the man hand-picked by the Prime Minister to lead Britain's war on terror are the latest setback to hit his policy of compiling a "government of all the talents".

Lord West has been married to Lady Rosie West, an artist, for 34 years and the couple have three children. The details of his private life emerged amid escalating rumours about his relationship with Ms Lyngstad, whom he is believed to have met at a charity function early last year.

Lord West, who is 59, denied yesterday that they were having an affair. He told the Mail on Sunday: "I just don't like talking about my private life."