John Hooper in Rome

Greenpeace activists occuped four coal-fired power stations in Italy yesterday, as G8 leaders met in L'Aquila to discuss issues including action on climate change. More than 100 Greenpeace activists from 18 countries took part in the protests to draw attention to the group's campaign for action by world leaders on cutting greenhouse gas emissions.

In Rome, activists from Oxfam International donned masks of world leaders and dressed up as chefs, stirring a mock Earth in a pot representing the planet's rising temperature.

The climate change protests came a day after anti-globalisation groups in the capital blocked roads and rail tracks and clashed with police in violent protests against the G8. Nearly 40 activists were detained.

One of the Greenpeace targets yesterday was Italy's biggest coal-burning power station, at Brindisi in the south-east of the country, where protesters climbed the chimney and occupied the conveyor belt carrying coal into the plant.

A local news agency quoted one of the demonstrators as saying the power station's management had started the belt while the Greenpeace activists were still on it. "At first, they didn't know we were on the conveyor belt", said Serena Bianchi. "Then we went to tell them, but even then we had some difficulty in persuading them to stop everything."

The organisation also occupied working plants near Venice and Genoa and staged a protest at an old oil-fired power station at Porto Tolle in northern Italy that is being converted to coal.

The UK activist Ben Stewart, who previously climbed the Kingsnorth coal power station in 2007 and today climbed a 160ft chimney at a site near Venice, said: "Politicians talk but leaders act. The G8 leaders must stop putting the interests of big coal and other climate polluting industries ahead of the planet and take strong, decisive leadership on climate change."

Three of the four power stations occupied today belong to Italy's biggest electricity generator, ENEL. A spokesman said the company had no comment to make.