"We regret that it has been hard to reach agreement with the US administration, but now we are delighted that there is a wide-ranging public debate about the issue in America," Gabriel said on Monday after holding talks with US House of Representatives leader Nancy Pelosi in Berlin.

"I believe Germany's policy on climate change is the right one," he said. "We want to take concrete steps forward."

The US Democratic party leader, who is an outspoken critic of President George W. Bush, was in Berlin on the first stop of a European tour, accompanied by a delegation of high-ranking Democratic and Republican politicians.

"This trip for us began in Greenland where we saw first-hand evidence that climate change is a reality," Pelosi said at a press conference. "There is just no denying it."

"I hope that we can all assume our responsibilities with great respect and that our administration will be open to listening to why it is important to go forward, perhaps in a different way than we have proceeded in the past," she said.

Global danger

Since Democrats took over Congress in January, both the House and Senate have proposed to push the nation more aggressively to reduce carbon emissions.

Leaked documents, however, have shown that Washington is raising strong objections to a proposed global warming declaration prepared by the German hosts for the June 6-8 summit of the leaders of the Group of Eight most industrialized nations in the Baltic Sea resort of Heiligendamm.

Pelosi declined to say whether Washington would sign up to the German proposal of limiting the worldwide temperature rise this century to two degrees Celsius and cutting global greenhouse gas emissions to 50 percent below 1990 levels by 2050.

"First we have to have a fundamental agreement as to what the challenges and possibilities are for reaching such a goal," she said. "The science is clear, the challenge is undeniable, we have to work together though to reach a solution."

"All of us are committed to finding the best possible science and workable solutions to the challenges we face."

German leadership

Pelosi said she would thank Chancellor Angela Merkel for her "leadership" on the climate change issue when they meet on Tuesday.

But in another sign of the obstacles facing Germany, India, which has been invited to participate at Heiligendamm, said Monday it would reject proposals to limit greenhouse gas emissions because stricter restrictions would slow its booming economy.

Gabriel said developing nations like China and India could only be persuaded to commit to climate change restrictions if the most industrial nations such as Germany and the United States led the way.

"We must take joint responsibility," the minister said.