HIROSHIMA — At a memorial ceremony attended for the first time ever by a U.N. secretary general and a U.S. representative, Hiroshima on Friday marked the 65th anniversary of its atomic bombing by calling on Japan to withdraw from the U.S. nuclear umbrella and accelerate the progress made over the past 18 months to eliminate nuclear arms.

On a sweltering morning, Prime Minister Naoto Kan, U.N. Secretary General Ban Ki Moon, U.S. Ambassador John Roos, as well as representatives of nuclear states Great Britain and France were on hand for the ceremony. Some 55,000 people took part in the memorial, according to city officials.

This year's ceremony took place three months after the Nuclear Nonproliferation Review Conference in New York, which followed an April meeting hosted by the U.S. on nuclear disarmament.