Angela Merkel is expected to announce the suspension of plans to extend the life of Germany's nuclear power stations, after the nuclear emergency triggered by Japan's devastating earthquake.

After two hydrogen explosions at the Fukushima Daiichi reactor in Japan, the German chancellor has decided to re-examine her highly controversial decision last year to renew the country's 17 nuclear plants for an average 12 years, German media is reporting.

Government sources are reported to have said that Merkel took the decision on Sunday night after a crisis meeting at the Berlin headquarters of her Christian Democratic Union (CDU) party. She is expected to confirm the suspension at a press conference with her foreign minister, Guido Westerwelle, at 4pm (3pm GMT).

Switzerland has announced it is suspending plans to build new nuclear power stations. 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 approved three sites for new nuclear power stations after the plans were submitted in 2008.

Earlier on Monday, Westerwelle told reporters that he could imagine a temporary halt in Germany's nuclear renewal programme. "You can't cut costs where safety is concerned," he said. Germany's environment minister, Norbert Röttgen, said: "Even in the CDU, we are having to have a new debate [about nuclear power] because we are in a new situation."

In Monday's newspapers, the opposition parties demanded a rethink on Germany's nuclear policy. Sigmar Gabriel, head of the Social Democrat party, said: "We need to make clear that not only are the days of cheap oil over, but also the days of nuclear power." The Left party demanded an "immediate, irreversible and systematic dismantling" of Germany's nuclear power plants.

The European energy commissioner, Guenther Oettinger, said safety at older German nuclear power stations must be checked rigorously, and he refused to rule out closures if necessary. He told Deutschlandfunk radio that the crisis at the Japanese nuclear plant had changed the world and put into question what had been regarded as safe and manageable.

Oettinger, Germany's member of the European commission, said safety questions were primarily the responsibility of the 14 European Union states which used atomic energy, and that safety at Germany's older plants was constantly being upgraded. But asked if the older plants could be shut down, he said: "If we take it seriously and say the incident has changed the world - and much that we as an industrial society have regarded as safe and manageable is now in question - then we can't exclude anything."

Oettinger is a member of the CDU and a former premier of the south-western state of Baden-Wuerttemberg, where the party risks losing power in elections in two weeks, due partly to rising support for the Greens.

Merkel called a crisis meeting with senior ministers on Saturday to discuss the consequences of Japan's nuclear crisis after the massive earthquake and tsunami. As thousands protested in Baden-Wuerttemberg against her nuclear policy, Merkel said Germany's nuclear plants were safe but the government was watching the situation in Japan to see if lessons could be learned.

The decision last year to keep Germany's 17 nuclear plants running for about 12 years beyond their original shutdown date stirred large-scale protests and hit the ruling coalition's popularity.

On Saturday, anti-nuclear protesters formed a 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.