German chancellor Angela Merkel is calling for the G7 powers to throw their weight behind a pledge to find $100 billion to help poor countries tackle climate change.

Ms Merkel, who hosts the G7 summit starting tomorrow, cautioned against comparing the meeting with full-fledged climate negotiations, but said the world's leading industrial powers should send a signal ahead of a climate conference in Paris in December.

Governments agreed in Copenhagen in 2009 to seek the funding from public and private investors over several years for measures to rein in climate change.

Ms Merkel said in a video message that it is important to have a "confirmation of this 100 billion fund" from the G7, though detailed financing pledges will be made elsewhere.

Meanwhile, thousands of people are staging a protest in the German Alpine resort town of Garmisch-Partenkirchen ahead of the arrival of the G7 leaders.

The crowds demanded action on several issues including climate change, poverty and globalisation.

Police spokesman Hans-Peter Kammerer says the protests have so far been peaceful but that significant numbers of extremists from Germany, Austria, Italy and Britain were thought to be joining the expected crowd of some 8,000.

More than 22,000 police officers are on hand.

Protesters' spokesman Simon Ernst said they wanted to show their anger at the leaders of Germany, France, the US, Italy, Britain, Canada and Japan, calling them "the henchmen of bankers and corporations".