LONDON (AFP) - Tens of thousands of people across Europe demonstrated for action on climate change on Saturday, two days before world leaders gather in Copenhagen for landmark talks on tackling global warming.

Protesters in Stockholm, London, Brussels, Paris and Dublin took to the streets to call for a far-reaching international agreement on reducing greenhouse gas emissions at the UN-led talks starting on Monday.

In Stockholm, more than 200 protesters marched to the royal palace, arriving to the strains of Swedish pop band Europe's 1986 hit "The final Countdown."

As about 20,000 people marched through central London, British Prime Minister Gordon Brown promised to heed their concerns.

"I think the people of the world, being outspoken as we've seen in the demonstration today... they're propelling us as leaders to take the action that is necessary," Brown said after meeting some of demonstrators.

He added: "The scientific evidence is very clear, that there is a climate change problem we've got to address.

"All of the world now recognises this at a national government level and that's why Copenhagen is going to be the coming-together of governments to make an international plan to deal with climate change."

The summit is aimed at forging a new pact to tackle greenhouse gas emissions and their impact after the Kyoto Protocol expires in 2012, and will be attended by US President Barack Obama among other world leaders.

Belgian climatology professor Jean-Pascal van Ypersele, vice-chair of the Intergovernmental Panel on Climate Change, told AFP he was "very optimistic" that a deal could be reached.

Many of those protesting in London said it was a rare chance to take action, including Juliana Smith, 49, who said: "We are a normal family and this is our chance to say something. We feel powerless most of the time."