Pope Benedict XVI called Saturday for a new push towards nuclear disarmament, as he received the credentials of Japan's new ambassador to the Vatican, Hidekazu Yamaguchi.

Referring to the 65th anniversary in August of the nuclear bombing of Hiroshima and Nagasaki at the end of World War II, the pope said, "This tragedy persistently reminds us of the necessity to persevere in efforts to ensure non-proliferation of nuclear weapons and disarmament."

Speaking in French, the pope stressed that "the memory of this dark episode in human history becomes more poignant each year as the witnesses of such horror pass away."

Benedict said nuclear weapons were a major cause of concern, raising tension and mistrust in many parts of the world through their possession and threat of being used.

He hailed Japan for "its constant support in the search for political solutions which not only to prevent proliferation ... but to prevent war being considered as a way to resolve conflicts."

Both Tokyo and the Vatican shared the hope of a world without nuclear arms, the pope said, calling for weapons budgets to be spent on social and economic development, education and health instead.

He praised Japan for its freedom of religious observance, enabling Catholics to live in peace and fraternity and contribute to national life, as well as its aid for developing countries.