Pacific island and other small countries being punished by global warming will use a Commonwealth summit this week to ramp up pressure on powerful nations in the climate change debate. Setting the stage for the three-day event, Samoan Prime Minister Tuilaepa Sailele Malielegaoi hit out at major polluters the United States and China for not doing enough to cut their greenhouse gas emissions. \"The most disturbing revelation at our discussions this afternoon includes references to the two biggest countries that... do not seem to be forthcoming in their commitments to restricting their gas emissions,\" Tuilaepa said. He also called for rich nations to fulfill their promises to provide small countries with billions of dollars in funds so they can adapt to rising sea waters and extreme weather events that scientists blame on climate change. Tuilaepa was speaking to reporters late Tuesday after discussing climate change with foreign ministers and other representatives of more than 40 small island and developing Commonwealth nations in Perth. Tuilaepa said those countries would take a united stance on climate change during the summit of leaders from the 54-nation Commonwealth bloc starting on Friday. Smaller countries that are most vulnerable to climate change have long complained that their pleas for urgent action are being ignored. The Commonwealth Heads of Government Meeting (CHOGM), held every two years, is seen as a rare chance for them to have their voices heard above those of powerful nations in the contentious climate change debate. \"Often the countries who are left out of these deliberations are those who are most affected by climate change and the broader challenges of sustainable development,\" Australian Foreign Minister Kevin Rudd said. While CHOGM is not expected to produce any direct commitments from countries on fighting climate change, it is a chance to build political momentum ahead of a crucial United Nations summit in South Africa starting next month. \"Political will is a very important aspect in the success of any international process,\" the Commonwealth secretariat\'s chief environment adviser, Janet Strachan, told AFP. \"I would not underestimate the impact that face-to-face discussions by heads of state can have.\" The UN climate talks in Durban are one of the last chances for world leaders to forge a united stance on fighting climate change before the Kyoto Protocol, which governs greenhouse gas emissions reductions, expires at the end of 2012. However, the United States did not ratify Kyoto because developing countries, such as China, did not have to commit to targets on cutting emissions. The United States has said it will boycott any similar agreement that countries try to forge in Durban and beyond. China, meanwhile, refuses to agree to binding targets, citing the damage such measures would do to its economy and arguing that richer countries have the historic responsibility for the problem. Amid this debate, Pacific and other small island countries are already reporting dire, and in some cases near catastrophic, climate change consequences. \"Climate change remains the single greatest threat to the livelihoods, security and well-being of the peoples of the Pacific,\" leaders from 16 Pacific nations said after their own summit in Auckland last month. Kiribati President Anote Tong revealed then that his low-lying nation was considering radical solutions to deal with rising seas, such as moving its 100,000-strong population onto man-made floating islands.