Disaster puts pressure on governments, with protests in Germany and concern over new plant plans in Italy and the UK

Tens of thousands of people have taken part in an anti-nuclear demonstration in southern Germany. The demonstration had been planned for some time, but after the news of Japan's nuclear emergency, organisers were overwhelmed by crowds of around 50,000 people who turned up.

The demonstrators, who stretched in a 45km chain from Neckarwestheim power plant to the city of Stuttgart, were demanding that the German government move away from nuclear power.

Chancellor Angela Merkel, who has extended the lifespan of Germany's nuclear power plants, summoned senior cabinet ministers to an emergency meeting.

The Japanese radiation leak comes at a difficult time for Merkel, whose conservatives face three state elections in March where worries over nuclear safety could rally her opponents. The opposition Social Democrats and Greens have called for change and claim several German nuclear plants could not withstand a direct hit by an aircraft or an earthquake.

"We cannot master nature, nature rules us," said Renate Kuenast, the Greens' parliamentary leader.

The government's decision last year to keep Germany's 17 nuclear plants running for about 12 years beyond their original shutdown date has weighed on the popularity of Merkel's coalition.

In Italy a senior government politician said the earthquake would not change plans to move ahead with a new nuclear power scheme.

Italy is the only G8 industrialised nation that does not produce nuclear power, but prime minister Silvio Berlusconi wants to generate a quarter of the country's electricity from nuclear in the future.

Italy is also at high risk of suffering natural disasters, mainly due to earthquakes. "The position remains what it is, you can't keep changing it," Fabrizio Cicchitto, leader of Berlusconi's PDL party in the lower house told reporters. "It's not just recently that we have energy problems," he said.

In the UK the energy secretary Chris Huhne said the government was monitoring the nuclear situation in Japan. "It's too early to say what the cause was, let alone what the implications are. We are working extremely closely with the IAEA to establish what has happened. Safety is the number one priority for the nuclear industry."

Privately, many in government and the private energy sector in the UK are worried that the raising of the spectre of nuclear disaster will have implications for the coalition's huge building programme for ten new power stations to replace the UK's ageing reactors.

The accident in Japan comes days after the Navy admitted the reactors on British submarines are 'significantly below benchmarked good practice', and weeks before the 25th anniversary of the Chernobyl disaster, which will push fears over nuclear safety back to the forefront of the minds of the British public.

Jan Beranek, head of Greenpeace International Nuclear Campaign, asked for the construction project to be scrapped in the wake of the Japanese earthquake. "Governments should invest in renewable energy resources that are not only environmentally sound but also affordable and reliable," he said.