Outraged poor nations bearing the brunt of global warming have become increasingly bold in UN-led climate talks, but some worry that recent meetings of large countries are sidelining their voices.

A grouping of 192 countries under the United Nations is leading the way in negotiating a groundbreaking climate change treaty, and most of its members are currently in Bangkok to try to hammer out a two-year work plan.

The meeting comes soon after the United States chaired a meeting of 16 nations most responsible for global warming, and ahead of a special climate summit on the sidelines of the Group of Eight summit of rich nations.

"We haven't been invited to either of those processes," Espen Ronneberg, a Samoa-based climate change advisor to the Association of Small Island States, said on the sidelines of the Bangkok talks.

"We need to have a global consensus on climate change, so to have a separate process that is not completely inclusive is not that helpful."

While major developing nations such as China and India are part of the big initiatives, the Group of 77, a bloc of developing nations, said it has not been invited.

"The balance has to come from everybody, all the representative groups, being around the table. Not specialised specific groups which have almost the same purpose -- that's a problem," said Byron Blake, deputy representative to the United Nations of current G77 chair Antigua and Barbuda.

The world has until 2009 to draft a new pact on battling global warming, which should come into force by 2012, when current Kyoto Protocol targets for rich nations to slash greenhouse gas emissions expire.

A report by the world's leading climate scientists last year warned that drought, floods and storms will increase as global temperatures rise, hitting poor countries hardest.

As they see climate change begin to affect their environments and economies, impoverished nations are becoming more vocal, said Antonio Hill, policy adviser to development group Oxfam.

"There is a very dramatic difference between this year and last year in the negotiations versus 10 years ago or even five years ago," he said.

Developing countries want the rich world to commit to ambitious cuts in greenhouse gas emissions -- which trap the sun's heat and cause global warming -- and pledge to transfer 'green' technologies and fund climate change-battling initiatives in poorer countries.

Many rich nations led by the United States, however, are pressing for developing countries also to commit to slashing emissions. They argue that the lines have blurred between rich and poor nations, with China expected soon to be the world's top emitter.

US President George W. Bush launched his own climate initiative, gathering 16 large nations responsible for 80 percent of the world's harmful emissions, which met two months ago in Hawaii.

Japan, meanwhile, will hold separate talks on the sidelines of the Group of Eight meeting in July, and has invited Australia, Brazil, China, India, Indonesia, Mexico, South Africa and South Korea to join.

The UN's climate chief Yvo de Boer told AFP that the new initiatives could be constructive, so long as they feed back into the UN-led efforts.

"The (US-led) major economies process and the outcome of the G8 meeting last year very clearly recognises that there is only one place where the real negotiations happen and that's the (UN) Convention on Climate Change," he said.

Blake urged big polluters to listen to all voices, rather than focus on sideline initiatives.

"It is almost a defensive move by a club of people who have been the cause of the major problems," Blake told AFP.

"Naturally they are going to see how to create a so-called solution which will have least impact on themselves, where they have to make the least contribution," he added.

John Ashe, current chairman of the G77, said they would welcome an invite to the G8 discussions on climate change, but added that world leaders were free to convene any meetings they pleased.

"If their leaders can bring ideas to the table I'm sure we would all be willing to listen to those ideas," he said.