Issei Kato

HIROSHIMA, Aug 6 (Reuters) Tens of thousands of people from around the world gathered in Hiroshima today to pray for peace and urge the world to abandon nuclear weapons on the 61st anniversary of the first atomic bombing.

In an annual ritual to mourn the more than 220,000 people who ultimately died from the blast, a crowd including survivors, children and dignitaries gathered at the Peace Memorial Park, near ground zero where the bomb was dropped.

''Radiation, heat, blast and their synergetic effects created a hell on Earth,'' said Hiroshima Mayor Tadatoshi Akiba.

Lamenting a global trend towards nuclear proliferation, Akiba called for a campaign to free the world of atomic weapons.

''Sixty-one years later, the number of nations enamoured of evil and enslaved by nuclear weapons is increasing,'' Akiba told the crowd gathered under a blazing summer sun.

''The human family stands at a crossroads. Will all nations be enslaved? Or will all nations be liberated?'' The Peace Bell tolled at 8:15 a.m. - the moment the Enola Gay B-29 warplane dropped the bomb on August. 6, 1945 - as the crowd stood and bowed their heads for a moment of silence.

The United States dropped a second atomic bomb on the southern city of Nagasaki on August 9.

Six days later, Japan surrendered.

Prime Minister Junichiro Koizumi vowed to abide by Japan's pacifist constitution and non-nuclear policy.

''Japan, the only country that has suffered atomic bombings in the human history, has the responsibility to keep telling the international community about its experience,'' Koizumi said.

''With the resolve not to let the tragedy of Hiroshima and Nagasaki repeat itself anywhere, Japan has delivered on its pledge not to wage war in the past 61 years.'' MORE REUTERS DH PM0811