The crisis in Japan has revived anti-nuclear passions around the world, putting governments on the defensive and undermining the nuclear power industry’s recent renaissance as the clean energy of the future.

In the most dramatic move, German Chancellor Angela Merkel announced Tuesday that all seven of the country’s nuclear power plants built before 1980 would be shut down, at least for now, as safety checks are conducted. The decision came one day after the government, facing strong public opposition to nuclear energy ahead of upcoming regional elections, suspended plans to extend the life of its aging plants.

Switzerland, with five reactors, announced Monday that it would freeze plans to build or replace nuclear power plants, and Austria called for new stress tests on plants across Europe.

Yet other countries, including Italy, where a Franco-Italian partnership is planning to start construction on a nuclear plant in 2013, have called for calm, with authorities saying the crisis should not derail plans to expand nuclear energy.

White House officials defended the use of nuclear power in the United States, which President Obama has embraced throughout his administration. “At this time, we don’t have any information that would cause us to do anything different,” Gregory B. Jaczko, chairman of the Nuclear Regulatory Commission, said at a White House briefing Monday.

In France, where nuclear plants produce 80 percent of electricity, the Japanese calamity reenergized a long-dormant political debate about the country’s heavy reliance on nuclear power.

Government officials sought to reassure the public that France’s more than 50 nuclear plants are safe, and President Nicolas Sarkozy told his political coalition that the plants were among the safest in the world.

The main opposition Socialist Party was divided, with key leaders saying it would be foolhardy to abandon a nuclear energy program that has stood since the 1970s but several Socialist figures demanding a reconsideration of nuclear safety measures.

Europe Ecology-Greens Party activists, long opposed to nuclear power, called for a referendum on whether France should get out of the nuclear business and accused the government of playing down the risks.

“We have to end the myths,” said Cecile Duflot, a prominent Green leader. “Zero-risk nuclear power production does not exist.”

In Russia, Ukraine and Belarus — which will mark the 25th anniversary of the Chernobyl disaster this April — the crisis in Japan has served as a reminder of the dangers of nuclear power, but national leaders say they don’t see any alternative.

Russia is building six new nuclear power plants and has plans for more. It also recently signed an agreement with Belarus to build one there.

Ukrainian Prime Minister Mykola Azarov said Tuesday that Kiev is moving ahead with plans to build two new reactors at the Khmelnytsky power plant. “I believe there is no possible alternative to the use of nuclear energy,” he said at a news conference during a visit to Istanbul, “and only rich countries can afford to discuss the possibility of closing” nuclear plants.

Environmental groups disagree. “The example of Japan vividly demonstrates that even if properly maintained, nuclear power engineering is extremely dangerous,” Greenpeace Russia head Ivan Blokov told Interfax on Monday.

In Britain, where officials have laid out plans for a new generation of 10 nuclear power plants, the government has commissioned a fresh report on nuclear safety, while opponents vowed a new campaign of public pressure.

“The risks from nuclear energy remain unchanged; there were always risks,” said Stephen Tindale, a British environmentalist. “But they will clearly need to be properly reassessed in the light of what’s happening in Japan, and that’s inevitably going to mean that the nuclear renaissance is going to be a smaller renaissance than it would have been.”

Even in tightly controlled China, a debate on nuclear safety seemed to be underway.

According to the London-based World Nuclear Association, China has 13 nuclear power reactors in operation and 27 others under construction. An additional 50 reactors are in the planning stage, and more than 140 others have been proposed, the association says. China, like Japan, is prone to earthquakes.

Government officials have said China’s nuclear program, the world’s most ambitious, will continue unabated, but they have also tried to allay fears about the potential dangers. Officials have said the plants being built here, unlike Japan’s older plants, are new-generation models that do not rely on electrical power for their cooling systems but instead are fitted with large tanks of water operating by gravity in the event of a crisis.

But concern about the possibility of a nuclear leak in China dominated discussions on the country’s burgeoning microblogging sites, the country’s newest forum for the public to voice unfettered views.

“How many nuclear power plants are there in our country? Are they all far away from the seismic zones . . . ?” Zheng Yuanjie, a well-known author of children’s books, wrote on his microblog.

In Taiwan, environmentalists, civil engineers and the opposition party called for the government to immediately halt construction of a fourth nuclear plant, slated to go online in late 2012. Just 100 miles off the coast of China, Taiwan lies on the same arc of tectonic plates as Japan.

Trying to allay public fears, President Ma Ying-jeou ordered safety checks Tuesday of Taiwan’s three existing plants but dismissed calls to put the fourth plant on hold.

In India, activists and villagers who have waged a two-year struggle against a proposed nuclear plant in Jaitapur, in Maharashtra state, said the events in Japan have given them a new tool to fight the government.

“What is happening in Japan has reenergized our opposition to the nuclear plant here,” said Vaishali Patil, an anti-nuclear campaigner.

The proposed plant will be built by the French company Areva. India now has 20 nuclear reactors in seven power plants.

The Indian government set aside sites for American, French and Russian-built nuclear reactors across the country after New Delhi signed a landmark 2005 nuclear accord with the Bush administration.

India’s environment minister, Jairam Ramesh, said Tuesday that “if additional safeguards have to be built in as part of the environmental clearance, we will certainly look at it.”

Staff writer Perry Bacon in Washington, correspondents Anthony Faiola in London, Edward Cody in Paris, Will Englund in Moscow and Rama Lakshmi in New Dehli, special correspondent Amber Parcher in Taipei and researchers Zhang Jie and Wang Juan in China contributed to this report.