Colin Heseltine, executive director of the Asia Pacific Economic Cooperation (APEC) forum secretariat, said Australian Prime Minister John Howard has written to other leaders indicating his desire for a discussion on the issues.

"A major issue that has rapidly emerged at the top of APEC leaders' priorities this year is to develop a coherent regional policy response to... big challenges now facing APEC member economies: energy security and climate change," Heseltine said.

Energy security refers to the need to ensure long-term energy supplies.

Howard, who will host this year's summit in Sydney, "has written to his APEC counterparts indicating that he would like APEC leaders to consider ways in which APEC can support an emerging, practical consensus on a global framework for tackling climate change," Heseltine added.

Heseltine, a senior Australian diplomat who holds the secretariat's revolving leadership, was speaking at a forum in Singapore organised by the Australian Chamber of Commerce.

APEC's 21 member economies, stretching from China to Chile, account for 60 percent of global energy demand. Across the grouping, energy demand is expected to double by 2030, he said.

APEC includes the world's two largest emitters of greenhouse gases -- the United States and China. It also covers Indonesia, which by some estimates is the third biggest source of greenhouse gas emissions, Heseltine said.

Carbon dioxide from energy use is a major contributor to the greenhouse gases that scientists blame for the earth's warming.

The Asia Pacific leaders are also expected to take a "fresh look" at ways to promote regional economic integration, he said, as World Trade Organisation (WTO) talks to free up trade are in limbo.

Work on a report by senior officials on promoting regional economic integration is "well in advance" and will be presented to the leaders in Sydney.

This will include the idea of a Free Trade Area in the Asia Pacific (FTAAP), Heseltine said, adding that this was for the long term.

"Of course we know it is a long way off. To be realistic, this is not something that's going to happen any time soon," he said.

Some APEC members, led by the United States, have raised the FTAAP as an alternative plan in case WTO talks collapse altogether due to unresolved disputes over farm subsidies.

APEC trade ministers who met in Australia earlier this month pledged strong support for the WTO talks but said they were also examining the possibility of an Asia Pacific free trade area.