Former United Nations chief Kofi Annan on Tuesday urged the world's richest nations to take the lead in tackling the impact of global warming on developing countries.

Annan said attempts to forge a global agreement on climate change by the end of the year should focus on the "overwhelming destruction that climate change is causing and will continue to cause" on the world's 50 poorest nations.

Yet the least developed countries account for just one percent of greenhouse gases, according to a recent report by Annan's Global Humanitarian Forum.

"It is this injustice -- as well as the urgency and the scale of the crisis -- which must be at the forefront of the minds of those with responsibility for reaching agreement at Copenhagen later this year," Annan told the forum's annual meeting.

Six months before a landmark climate change conference in the Danish capital, negotiators wrapped up talks last week hinting that there had been no progress on the core issue of how to share the burden of future emissions cuts.

The former UN secretary general urged developed economies to lead efforts for "deep, binding and fair" targets to cut emissions of greenhouse gases.

"Those developed economies most responsible for past and present emissions must take the lead," he said.

"Without them accepting responsibility, the rapidly developing economies will understandably resist the changes in their economies which are also needed," he warned.

Environment ministers from the world's major economies -- and the largest polluters -- including the United States and China, were meeting in Mexico on Tuesday.