Small island nations have criticised Saudi Arabia at UN climate talks for blocking a proposed study of tougher curbs on global warming that could slow a feared rise in sea levels.

The row, the most public during May 31-June 11 talks on a new climate pact, exposed deep rifts between developing nations which usually present a united front to put pressure on rich nations to cut their greenhouse gas emissions.

'The survival of entire nations is at stake,' said Selwin Hart of Barbados on Thursday, speaking on behalf of the Alliance of Small Island States after Opec nations blocked a proposal to commission a UN study of climate science since 2007.

'We find it ironic and alarming that our fellow developing countries would block such a paper that would assist other developing countries,' he told delegates.

Saudi Arabian delegates said the proposed study would be too complicated and wanted assurances that it would also encompass issues such as the impact on exporters of goods ranging from tomatoes and rice to coal and oil.

Many developing nations, and rich nations including the European Union and Australia, backed the proposed study and expressed disappointment after it failed to win the needed unanimous support. Countries including Qatar and Kuwait spoke in support of Saudi Arabia.

Opec states fear that any steps to tighten curbs on global warming will hit their economies by hastening a shift from fossil fuels to cleaner energies such as wind or solar power.

Small island states want to limit any rise in world temperatures to below 1.5 degrees Celsius (2.8 F) above pre-industrial times - and proposed asking the UN Climate Change Secretariat to review science on the issue by November.

Most nations favour a less stringent limit to keep global warming below 2 C, agreed by most nations at the UN's Copenhagen summit. Seas are set to rise this century because of melting ice and because water in the oceans expands as it warms.

Wendell Trio of environmental group Greenpeace criticised Saudi Arabia, saying people in some island nations 'could become stateless from sea level rise' and desperately needed the latest scientific information to plan.

The UN talks are preparing for an annual ministerial meeting in Mexico from November 29 to December 10. Many delegates say a treaty is out of reach but are hoping for progress on issues such as new climate funds or on protecting tropical forests.

Separately, 287 non-governmental groups issued a letter urging President Barack Obama to stop backing the World Bank as the channel for climate funds to developing nations.

'The World Bank has lent money to dirty fossil fuel projects again and again,' Karen Orenstein of Friends of the Earth US said.-Reuters