The mayors of Japan's Hiroshima and Nagasaki, the world's only cities to have been hit with atom bombs, on Friday hailed a UN resolution vowing to rid the planet of all nuclear weapons.

The Fat Man mushroom cloud resulting from the nuclear explosion over Nagasaki rises 18 km (11 mi, 60,000 ft) into the air from the hypocenter

"This is what we have consistently demanded," said Nagasaki mayor Tomihisa Taue. "I am grateful to see that the United Nations is heading in the same direction as us. This will be an epoch-making, great turning point."

Hiroshima mayor Tadatoshi Akiba also praised the resolution and welcomed a speech to the United Nations by Japan's Prime Minister Yukio Hatoyama, who joined calls to rid the world of the "cruelty" of nuclear weapons.

Akiba said in a statement that the centre-left premier had signalled "a leading role in acting on the wishes of the hibakusha (atom-bomb sufferers), which is that 'we must never inflict this agony on anyone else.'"

Hatoyama said at the 15-member UN Security Council: "I would like to encourage all leaders of the world to visit Hiroshima and Nagasaki and absorb with their own eyes and ears the cruelty of nuclear weapons."

The Security Council vowed at an unprecedented summit hosted by US President Barack Obama Thursday to work to rid the planet of all nuclear arms.

Obama became the first American president to chair a meeting of the UN Security Council as the United States -- the only nation to have unleashed a wartime atomic bomb -- holds the body's rotating presidency this month.

In Hiroshima, more than 140,000 people were killed instantly or died in the weeks that followed August 6, 1945 when US forces dropped an atomic bomb on the city. Three days later, a second atomic bomb was dropped, killing some 70,000 people in Nagasaki. Japan surrendered on August 15, ending World War II.