Tony Blair has insisted the whole world is now united in its determination to tackle climate change.

Hailing the success of the UK-organised summit on climate change in Mexico, the Prime Minister said the involvement of developing countries such as India and China was "very important for the future".

Mr Blair was speaking in Downing Street as Environment Secretary David Miliband wrapped up the two-day meeting by urging large-scale investment in new technologies to help reduce carbon emissions.

The Prime Minister said: "The G8 Plus Five meeting that has been happening in Mexico on climate change is a very important indicator of the desire of the world now to come together and deal with the issue of energy and the environment and how we make sure there is sustainable growth in the future.

"And the fact that you have got a dialogue now that involves America and India and China, as well as the European countries, is obviously very important for the future.

"So that is good and it will give us a chance, this energy discussion, to talk about energy security and environ-mental issues too."

The conference in Monterrey was the latest round of talks on the climate action plan decided upon at the G8 Gleneagles Summit last year.

Ministers from G8 nations have been joined at the event by representatives from the emerging economies of China, India, Brazil, and South Africa.

Mr Miliband told delegates the threat from climate change was now so severe that "business as usual is not an option".