The informal meeting has agreed on a three-year programme setting special targets to ratify the Kyoto deal made last year, which set a legally binding global 8% cut in greenhouse gases by 2010.

Nations agree

The Kyoto protocol set industrialized nations targets for cutting emissions of greenhouse gases, but failed to agree how emission cuts could be traded among countries.

The agreement between 20 nations, including Japan and the United States, will now be put before 140 countries at a UN conference in Buenos Aires in November.

Greenhouses must be cut by 8%

Ministers will then sort out ways of allowing countries to use credits from reductions in gases in other nations to meet their targets.

Recent flooding in Texas and Bangladesh, and the disastrous El Nino effect have in the last year reinforced the need to slow down the growth of carbon dioxide in the atmosphere.

According to UN estimates, current emission trends of heat-trapping gases are likely to cause average global temperatures to rise by 1 to 3.5 degrees Celsius over the next 100 years.

'British initiative'

Mr Prescott described the Tokyo talks as "another British initiative to take forward the consensus towards ratification".

He said: "This is what matters, and what is important is that we have secured the full support of ministers from America, Europe and Japan.

"Our discussions have been frank and meaningful on many deep issues and have built on the political will."

The deal is a boost for the deputy prime minister, whose visits to countries in the run-up to the Kyoto conference helped smooth over differences before the final negotiations.