Bono, the lead singer of U2, yesterday met the US Secretary of State, Mr Colin Powell, in Washington to discuss AIDS, Africa and debt relief.
A senior State Department official said the appearance of Bono, wearing "black and an ear-ring", had sent a thrill of excitement through some of the younger staff in the usually staid building.
A State Department spokesman, Mr Richard Boucher, said that Mr Powell "kept his cool" in the presence of Bono, declining to comment on whether the Secretary of State was a fan of U2.
"He didn't express any opinion one way or the other," Mr Boucher told reporters, insisting the meeting had been "serious" with music mentioned "only on the side".
Mr Boucher said that Bono, who has intervened on numerous occasions with world leaders, championing causes including debt relief for developing countries and the fight against AIDS, had "welcomed" Mr Powell's positions on these issues.
Bono is the spokesman for the Jubilee 2000 Coalition, an international campaign for the cancellation of debts which the world's poorest countries are unable to repay.
"We're in a new age," Mr Boucher said. "We're in a democratic age when there are a lot of players besides the government, and we're going to work with everybody who can help us achieve our goals."
Another State Department official commented: "There are serious players out there in the private sector and Bono is one of them."
He pointed out that Mr Powell had planned a meeting last week with Paul McCartney to talk about eliminating landmines but the former Beatle had been unable to visit Washington because of bad weather.