UN Secretary General Ban Ki-moon called yesterday for renewed international efforts to tackle the twin threats to the world posed by nuclear weapons and climate change.

Mr Ban told the annual meeting of the World Federation of UN Associations there was a rare but critical opportunity to create a safer world.

"For the first time in a decade, negotiators have agreed to a package of measures that can move the world away from nuclear weapons," he said of talks between Russia and the US on cutting their nuclear arsenals.

"Now is our time... the time to build on this momentum," Mr Ban told some 250 delegates from UN associations in 63 countries.

He called for a global push for a nuclear-free world. "We call it WMD - not Weapons of Mass Destruction but instead We Must Disarm."

The US and Russia last month ended a fourth round of talks in Geneva on a successor to the 1991 Strategic Arms Reduction Treaty, which expires in December.

They agreed to meet again in a month.

At a July summit in Moscow US President Barack Obama and his Russian counterpart Dmitry Medvedev agreed on a roadmap for a new treaty that sets numerical targets for further cuts in warheads and missiles.

Hans Blix, a former top UN nuclear inspector who leads the World Federation of UN Associations, echoed Mr Ban's call. The world's military spending hit 1.4 trillion dollars in 2008, he said.

"It is time to wake up to the tremendous threats and wasted costs by our addiction to excessive armament," remarked Mr Blix.

Mr Ban also raised the threat of global warming caused largely by greenhouse gas emissions.

The UN is orchestrating crucial talks in the Danish capital in December, in hopes of an agreement on slashing greenhouse gas emissions.

"We have less than 10 years to halt the global rise in greenhouse gas emissions if we are to avoid catastrophic consequences for people and the planet," Mr Ban told yesterday's forum.

"This December, in Copenhagen, we have a chance to put in place a climate change agreement that all nations can embrace." He called for "a major 'top down' push from world leaders" and also "a strong 'bottom-up' push" from the world's UN associations.

"We must seize this once-in-a-generation chance," Mr Ban said.

Mr Ban, a former South Korean foreign minister, is on a 10-day private visit and returns to New York on August 18.