Prime Minister Tony Blair said Tuesday that the threat of climate change was the most pressing long term issue facing the world and reaffirmed Britain's commitment to the Kyoto Protocol on global warming.

"We have to act and we have to act now," said Blair, at the launch of a new organization that aims to speed up cuts in greenhouse gas emissions.

The prime minister said it was important the issue of global warming was discussed at the forthcoming G8 summit in the United States.

The 1997 Kyoto Protocol sets the target of bringing emissions of carbon dioxide and other greenhouse gases worldwide eight percent below the 1990 level by 2010.

Washington has drawn fire from other countries for rejecting the protocol as based on flimsy evidence and harmful to the economy.

Blair was speaking at the launch of the Climate Change Group, which brings together leading corporations, financial institutions, civil organizations and state, city and national governments to accelerate greenhouse gas emission reductions.

"I think that there is a fair recognition around the world that something is happening to our climate," he said.

But there was also a debate "that there's some kind of trade off between economic growth and environmental protection and that if we improve the protection of the environment we may inhibit our ability to grow and enjoy rising living standards. Each of these issues has to be confronted," Blair added.

"We believe in the Kyoto Protocol and we believe it is essential that we have it implemented."