Pelosi is in Germany as part of a European tour to highlight congressional concern about climate change. "I emphasised that we are of the opinion that we need multilateral agreements in the future if we are to combat this global challenge on a global level," Merkel told reporters after meeting Pelosi and a bipartisan delegation of key House members.

Bush has been blocking an emerging consensus within the G8 in favour of firm targets for cutting carbon dioxide emissions.

Pelosi, the leader of the opposition Democrats which gained control of both houses of Congress last November, made it clear that she was siding with Merkel against Bush.

"I completely associate myself with the chancellor's comments that these solutions must be multilateral," she said.

US resistance to emissions limits has diminished hopes that the summit can pave the way for negotiations to expand and extend the Kyoto Protocol on climate change beyond 2012.

German Environment Minister Sigmar Gabriel told German television the G8 leaders could avoid failure by agreeing a clear mandate for the (UN) climate conference at the end of the year in Bali.

Washington is demanding that all quantitative targets for combating global warming be removed from a G8 draft communique prepared by the Germans and wants all references to the December Bali meeting watered down, according to a copy seen by Reuters.

The United States is the world's biggest emitter of carbon dioxide, while Germany is Europe's biggest air polluter.

The Bush administration withdrew from the Kyoto Protocol in 2001. Despite pressure from Germany, Britain and other allies to accept mandatory "greenhouse gas" limits, Washington mainly wants to focus on promoting environmentally friendly technology.

PELOSI PROMISES NEW LEGISLATION

On Sunday, Pelosi urged Bush to compromise with the other G8 members -- Germany, Britain, France, Italy, Japan, Canada and Russia. She said US legislators were determined to tackle climate change and would soon be passing new legislation.

"We will have legislation probably by the fourth of July," she said, adding that further legislation would be introduced later in the year. She gave no details.

Both Merkel and Pelosi expressed support for green technology, the centrepiece of Bush's environmental policy.

"We agree that technological development and innovation are key," Merkel said about her discussion with Pelosi.

G8 envoys met last week to try to iron out their differences on climate change but failed to bridge the gap, according to one official familiar with the talks.