Outside U.N.-led talks in Poland aimed at pushing 187 countries toward stiffer targets to fight global warming , some 1,000 demonstrators said governments were risking the planet's future by delaying action to squabble over who was to blame.

Several thousand more protesters took part in a march through London to demand "urgent and radical action" from the British government on climate change.

"So far I think it's going really slowly," Susann Scherbarth from Friends of the Earth in Germany said of the talks in the western city of Poznan.

She and other protesters in Poznan waved a banner reading: "Stop clowning around, get serious about climate action."

Others carried pictures of seas inundating cities and villages, and the suited hand of a businessman squeezing the planet.

The march fell short of organizers' predictions of a turnout of several thousand and many inside the talks did not see it.

"It's not a matter for negotiators, it's a matter for politicians. They are the ones who have been blocking the whole process," said Rae-Kwon Chung, South Korea's climate change ambassador, adding that he was unaware of the event outside.

Marches, bicycle rides and other events were scheduled around the world on Saturday to mark a "Global Day of Action on Climate," said the Global Climate Campaign, an umbrella group for participants.

London police said between 4,000 and 5,000 people took part in a rally which organizers said was aimed at reminding governments not to let the issue of climate change slip down a global agenda dominated by the financial crisis.

"The current economic downturn does not make the catastrophic consequences of failing to deal with the climate crisis any less catastrophic," said Phil Thornhill, Britain's national coordinator of the Campaign Against Climate Change.