HIROSHIMA, Aug. 6 Kyodo -- The city of Hiroshima on Tuesday commemorated the 57th anniversary of its atomic bombing in 1945 by reiterating its pledge to continue to promote peace and expressing concern at the threat of nuclear war.

Hiroshima Mayor Tadatoshi Akiba delivered an annual peace declaration in which he vowed to do his utmost ''to create a 'century of peace and humanity'.''

At the same time, however, Akiba said, ''The probabilities that nuclear weapons will be used and the danger of nuclear war are increasing.''

It was the first annual memorial for A-bomb victims since the Sept. 11 terrorist attacks on the United States and subsequent U.S.-led military campaign in Afghanistan.

In the declaration, Akiba urged U.S. President George W. Bush to visit Hiroshima and Nagasaki and ''confirm with his own eyes what nuclear weapons hold in store for us all.''

Prime Minister Junichiro Koizumi attended the ceremony in the Peace Memorial Park in Naka Ward, his second attendance at the annual event.

As the only country to have been attacked by nuclear bombs, Japan has maintained the pacifist Constitution under the resolution that the tragedies of Hiroshima and Nagasaki not be repeated, Koizumi said.

The premier renewed his pledge to maintain Japan's three avowed principles of not producing, not possessing and not allowing nuclear arms on its soil, adding ''This position will not change.''

''The government will continue efforts to ask other countries to join the Comprehensive Test Ban Treaty for its early enforcement,'' he said.

Other participants included Health, Labor and Welfare Minister Chikara Sakaguchi, whose ministry deals with policies for the rehabilitation of A-bomb survivors, House of Councillors President Hiroyuki Kurata, Hiroshima Gov. Yuzan Fujita, Nagasaki Mayor Itcho Ito and United Nations University Vice Rector Ramesh Thakur.

The 50-minute ceremony started at 8 a.m. with Akiba and two representatives of A-bomb victims' family put two books under an arch-shaped cenotaph in the park which list names of 4,977 people newly recognized as A-bomb victims by the city government since Aug. 6 last year.

Koizumi, Akiba, other guests and representatives of A-bomb survivors and citizens offered flowers in front of the cenotaph.

As the peace bell resounded through the park, some 45,000 participants observed a minute's silence for the bomb victims from 8:15 a.m., the time when the U.S. B-29 bomber Enola Gay dropped the first nuclear weapon on the western Japan city 57 years ago.

Akiba then read a peace declaration highlighting the danger of nuclear weapons and urged the government to reject nuclear arms and renounce war, as well as assist all atomic-bomb victims, especially survivors living overseas.

Fujita and Thakur also delivered speeches at the ceremony.

In a speech read out by Thakur, U.N. Secretary General Kofi Annan said the Sept. 11 terrorist attacks ''gave new meaning and new urgency to the worldwide challenge of disarmament -- particularly when it comes to weapons of mass destruction.''

''We, the peoples of the world�cmust do all we can to run back the tide of nuclear proliferation and ensure that the terrible experience of Hiroshima and Nagasaki is never repeated,'' Annan said.

The number of victims from the atomic bombing in the city totaled 226,870 as of Monday. The blast and its aftereffects killed an estimated 140,000 people by the end of 1945.