US Vice-President Dick Cheney's chief of staff, Lewis I. "Scooter" Libby, spoke to a Time magazine reporter prior to the leaking of the name of a covert CIA agent, the reporter has told a grand jury investigating the issue.

Matt Cooper, who escaped a jail sentence when he agreed to testify in the case, told the jury that he spoke to Mr Libby as well as to Karl Rove, the deputy White House chief of staff and the top political adviser to US President George W. Bush.