PRAGUE (AFP) - The European Union and Japan decided to join forces in the battle against climate change and invited large countries to follow suit at a summit meeting in Prague on Monday.

"Japan and the EU are aiming at building a low-carbon society. We believe that it is necessary for the United States, China, Russia to participate in a responsible manner," Japanese Prime Minister Taro Aso told reporters.

US President Barack Obama vowed last month in Prague that the United States was "now ready to lead" on climate change, breaking with his predecessor George W. Bush, whose stance had long frustrated Europeans.

So far, the US has agreed to cut its carbon emissions to 1990 levels by 2020, while Europe has pledged to cut its own emissions by at least 20 percent of 1990 levels by 2020, and 30 percent if other advanced economies follow suit.

Japan, the host of the Kyoto Protocol on fighting climate change, has not announced its mid-term target yet, but it has pledged to reduce carbon emissions by up to 80 percent by 2050.

But the country is lagging badly behind in meeting its targets as the government hesitates at restricting industry amid an uncertain economy.

The EU and Japan said in a joint statement Monday that they recognised the "significance" of a report by the UN's Intergovernmental Panel on Climate Change (IPCC), recommending a 25-40 percent reduction in greenhouse gas emissions for industrialised countries by 2020.

They also urged developing countries to "develop or update their national action plans towards low carbon development... in a measurable, reportable and verifiable manner."

China, as a developing nation, did not accept cuts in greenhouse emissions under Kyoto, and it wants to see significant financial incentives from richer countries before it commits to reductions under the new pact.

European Commission chief Jose Manuel Barroso said the EU and Japan were working together for a successful summit in Copenhagen in December, which is expected to produce a new climate treaty to replace Kyoto when it expires in 2012.

"We believe that Japan is a very important partner for the process," Barroso said after the meeting chaired by Czech President Vaclav Klaus whose country is the current holder of the rotating EU presidency.

Klaus has been a consistent sceptic on the issue of global warming but he maintained a diplomatic front, saying "the discussion was at a level that I had no motivation to enter".