Speaking at the annual ceremony commemorating the world's first atomic attack, he described the recent explosions carried out by the two countries as "extremely deplorable".

Mr Obuchi said the Japanese Government was strongly urging both nations "to stop the development of nuclear weapons and missiles."

Prime Minister Obuchi: appeal to new nuclear nations

He told an audience of tens of thousands of people in Hiroshima - including the Indian and Pakistani ambassadors - that he was pressing the two countries to sign the comprehensive test ban treaty.

About 140,000 people were killed when the United States air force dropped an atomic bomb over Hiroshima on 6 August, 1945.

Three days later, the US dropped a second atom bomb on Nagasaki, killing 70,000 people. Japan surrendered unconditionally on 15 August, 1945.

The Mayor of Hiroshima, Takashi Hiraoka, said the nuclear tests by India and Pakistan had raised tensions in South Asia and shook the foundation of the world's non-nuclear proliferation movement.

"The people in Hiroshima feel a strong rage against the nuclear tests by the two nations, and worry about inducing a chain reaction of nuclear competition," he said.