The 11 nations that make up the Pacific Small Island Developing States wrote to members of the UN's most powerful body to argue that the threat they face from a warmer world and rising sea levels is comparable to armed conflict.

The 15-nation Security Council oversees threats to international peace and security.

"Climate change can devastate a country just as thoroughly as an invading army," Nauru's UN Ambassador Marlene Moses said as chair of the island nations' group.

Ms Moses said the Security Council must step in because the UN-led negotiations for mandatory cuts in greenhouse gases and assistance for the most vulnerable nations is stalled.

"If (the) international community fails to take immediate action, then it will be complicit in the extinction of entire nations," she said.

The group said climate change is contributing to severe food and water shortages in the Pacific and already making refugees of people in Vanuatu, Micronesia, Papua New Guinea, Tuvalu and the Solomon Islands.

The group's letter, sent by UN ambassadors from the 11 Pacific island nations, was pointedly critical of the UN Framework Convention on Climate Change that sponsored the last major climate summit in Copenhagen, Denmark last December.

A last-minute political agreement fell short on specific steps to cool the planet, but urged deeper cuts in emissions of carbon dioxide and other gases blamed for warming the globe. It also set up the first significant programme of climate aid to poorer nations and adopted a goal of holding the rise in global temperatures below two degrees Celsius.

A promised 30 billion US dollar (£21bn) fund over the next three years, scaling up to 100 billion US dollars (£69bn) a year by 2020, was a key element.