The world's biggest polluters, including rich and developing nations, have backed a "shared vision" for reducing global greenhouse gas emissions, but failed to set specific goals called for by environmental activists.

Wednesday's statement from leaders of the 16 so-called "Major Economies" came on the final day of the G8 summit of leading industrialised nations in Japan.

"Climate change is one of the great global challenges of our time," the joint statement said, adding that the 16 nations "recognised that deep cuts in global emissions will be necessary".

It said that all sides had agreed to "work constructively together to promote the success of the Copenhagen climate change conference", referring to the United Nations meeting scheduled for December 2009 aimed at reaching a new global treaty on reducing emissions.

No specific figures

But the statement gave no timeframes or specific figures for how much rich or developing nations should cut emissions blamed for global warming.

The annual G8 summit brings together the leaders of the United States, Japan, Germany, Britain, France, Russia, Italy and Canada.

Wednesday's talks of the 16 Major Economies added the leaders of Brazil, China, India, Mexico, South Africa, Australia, Indonesia and South Korea.

Talks on a new climate change pact have made little progress [GALLO/GETTY]

However, they said they would not be able to achieve the target without the participation of major emerging economies such as China and India.

The announcement was swiftly condemned as meaningless by critics in the scientific community.

Alden Meyer, a spokesman for the Union of Concerned Scientists, said that without an agreement on a base year there was no way to measure if states were living up to commitments.

"They could have made progress here by being more specific on the near-term commitments that industrialised countries were willing to make to reduce their own emissions, but they don't have agreement on that," he said.

'Gulf still wide'

Despite growing concern that the world is heating up, talks aimed at producing a new global climate change treaty by the end of 2009 have made little progress.

"The world is watching today's meeting," a Japanese foreign ministry official was quoted as saying as leaders gathered for Wednesday's meeting.

"This is the first major meeting of developing and developed countries' leaders since the Bali talks," the official told AFP, adding: "It's true that the gulf between the two is still wide."

Later on Wednesday the G8 leaders were due to hold talks with the so-called G5 rising powers - Brazil, China, India, Mexico and South Africa - on means to rein in soaring oil and food prices that are taking their toll on the global economy.

Also up for discussion are proposals to formally expand the G8 to include Brazil, India and China.