PM hails 'major progress' at summit

The G8, which last year agreed only to "seriously consider" a 50% reduction in emissions by 2050, said that it would "consider and adopt" the target subject to a new international climate change agreement.

The group of leading industrialised nations also agreed to stick to a 2005 pledge to double international aid by 2010, despite fears they could drop it in the face of the credit crunch.

Mr Brown said: "There has been major progress on the climate change agenda, beyond what people thought possible a few months ago. Countries which previously objected to setting overall targets have accepted these targets subject to there being an international agreement."

Mr Brown also announced his delight that the aid promises made at Gleneagles would be retained and announced a multibillion-pound investment in malaria nets, fighting infectious diseases and education in developing countries.

The target agreement come ahead of a major UN summit next year in Copenhagen to find a replacement for the Kyoto Protocol which expires in 2012.

Poorer countries are also to get a £40bn injection from world banks over three years to help them switch to cleaner energy production. That is expected to reach £150bn, once a £1.6bn commitment from the G8 nations and private investment is included.

The G8 also agreed a list of 25 areas where more prosperous countries can help by cutting energy use - including abandoning traditional lightbulbs and cutting power used by appliances on standby. Mr Brown said he hoped part of that switch would see ordinary families across Britain switch to electric or other less-polluting cars.

He said the agreement on aid for Africa - which would get half the extra aid agreed at the Gleneagles summit in 2005 - was "a successful step forward".

Ensuring fellow leaders did not step back from supporting poorer nations because of domestic economic woes was one of his main objectives going into his first summit as PM.