Germany today announced the temporary closure of its two oldest nuclear power stations and suspended plans to extend the life of all of the country's remaining plants as jitters over nuclear power spread across the world.

Switzerland also put on hold plans to build and replace nuclear plants and Austria's environment minister called for atomic stress tests to make sure Europe's nuclear facilities are "earthquake-proof". On Tuesday there will be an emergency meeting of European Union nuclear safety authorities and operators to assess Europe's preparedness in case of an emergency.

After two hydrogen explosions at the Fukushima Daiichi reactor in Japan, the German chancellor Angela Merkel decided to re-examine her controversial decision last year to renew 17 nuclear plants for an average of 12 years. Merkel announced a "three-month moratorium" while each plant was given a thorough safety check.As a result, Germany's two oldest nuclear power stations will be taken off the grid imminently, as they have already reached the end of their lifespan. They will only be reconnected if they pass strict safety checks, the chancellor said in Berlin.

Both plants are situated in states where there are regional elections later this month. One, Biblis A, is in Hesse, western Germany, and the other, Neckarwestheim I, is in the southwestern state of Baden-Württemberg. Merkel's Christian Democratic Party (CDU) is at risk of losing Baden-Württemberg for the first time since 1953, leading commentators to suggest the decision was partly politically motivated.

Most Germans are opposed to nuclear power, and Japan's problems have raised fears of the technology and strengthened the nuclear lobby and the opposition Green Party. A poll for the news channel N-TV on Monday showed 88% of Germans wanted plants shut sooner rather than later.

Merkel said Germany needs to continue using nuclear power while it switches over to renewable power sources to keep energy affordable and to ensure it is not dependent on importing nuclear energy from other countries where safety standards might be lower than those in Germany. However, the events in Japan "teach us that risks that were considered absolutely improbable are in fact not completely improbable," she added.

The Swiss energy minister, Doris Leuthard, said the suspension would affect all "blanket authorisation for nuclear replacement until safety standards have been carefully reviewed and if necessary adapted". Swiss regulatory authorities had given their stamp of approval to three sites for new nuclear power stations after the plans were submitted in 2008.

European energy commissioner Günther Oettinger said safety at older German nuclear power stations must be checked rigorously, and he refused to rule out closures. He told Deutschlandfunk radio that the crisis in Japan had changed the world and brought into question what had been seen as safe and manageable.

The government's decision last year to keep Germany's nuclear plants running for 12 years beyond their original shutdown date had stirred large-scale protests.

On Saturday, anti-nuclear protesters formed a 45km (27 mile) human chain from the city of Stuttgart to an older nuclear power plant that will be kept running longer because of the new policy. Between 50,000 and 60,000 demonstrators took part, according to police and organisers.

In the US, Barack Obama reaffirmed his support for nuclear power. At a White House press conference, the head of the Nuclear Regulatory Commission (NRC), Gregory Jaczko, said the 104 reactors in the US were built to withstand earthquakes and tsunamis. "Right now we believe we have a very strong programme in place," he said, adding that Japan had requested assistance from the NRC and two experts on boiling water reactors were en route.

Jaczko in his remarks gave no details on the magnitude of natural disasters US reactors could withstand. Twenty-three are identical models of the two reactors which exploded in Japan. Twelve are newer versions of that model. He also said any release of radiation would be highly dispersed by the time it travelled across the Pacific to Hawaii or the West Coast.

Jaczko's appearance was the second show of confidence in the nuclear industry since Sunday. The White House said in a statement that Obama continued to see nuclear power as part of America's energy portfolio. "The president believes that meeting our energy needs means relying on a diverse set of energy sources that includes renewables like wind and solar, natural gas, clean coal and nuclear power.

"Information is still coming in about the events unfolding in Japan, but the administration is committed to learning from them and ensuring that nuclear energy is produced safely and responsibly here in the US," the statement said.