WASHINGTON (AFP) – The unfolding nuclear disaster in Japan at reactors damaged by a massive earthquake and tsunami has led some lawmakers to call for putting the "brakes" on US nuclear development.

"I've been a big supporter of nuclear power because it's domestic -- it's ours and it's clean," Senator Joseph Lieberman told the CBS News television program "Face The Nation" Sunday.

Nevertheless "I think we've got to ... quietly and quickly put the brakes on until we can absorb what has happened in Japan as a result of the earthquake and the tsunami," said Lieberman, who is chairman of the Senate Homeland Security Committee.

Experts must then "see what more, if anything, we can demand of the new power plants that are coming online."

President Barack Obama wants to increase nuclear power as part of a US effort to decrease the nation's dependence on coal and foreign oil. The administration has allocated $18.5 billion in Department of Energy loan guarantees to spur nuclear development.

The Obama administration "is committed to the re-launching of the nuclear power industry as a key part of moving the country to a clean energy economy," a US official told AFP in December, citing benefits like reducing greenhouse gas emissions and creating jobs.

US Representative Edward Markey, a nuclear power critic, called for a moratorium on building reactors in seismically active areas on Friday, The New York Times reported.

The disaster in Japan "serves to highlight both the fragility of nuclear power plants and the potential consequences associated with a radiological release caused by earthquake-related damage," Markey said in a statement.

"We must ensure that America's nuclear power plants can withstand a catastrophic event and abide by the absolute highest standards for safety," Markey said.

He sent a letter to the Nuclear Regulatory Commission seeking details on emergency plans for the US nuclear industry.

Nuclear energy however still has supporters on Capitol Hill.

Senator Charles Schumer told NBC's "Meet the Press" on Sunday that the unrest in oil-rich Libya is evidence that "we do have to free ourselves of independence from foreign oil."

"Prices are up. Our economy is being hurt by it or could be hurt by it. So I'm still willing to look at nuclear. As I've always said it has to be done safely and carefully," the New York Democrat said.

Senate Minority Leader Mitch McConnell told the Fox News Sunday program that lawmakers shouldn't make snap judgments.

"I don't think right after a major environmental catastrophe is a very good time to be making American domestic policy," the powerful Republican said.

Friday's colossal 8.9 earthquake and subsequent tsunami, which sparked an emergency at two of Japan's nuclear power plants and could result in catastrophic meltdowns, has many US nuclear energy advocates thinking twice.

Part of a reactor at Japan's aging Fukushima No. 1 atomic plant blew up Saturday, a day after the biggest quake ever recorded in Japan unleashed a 10-meter (33-foot) tsunami.

Japanese Prime Minister Naoto Kan said according to Kyodo News that the Fukushima plant, where crews are struggling to control overheating reactors, was still at an an "alarming" state.

Excessive radiation levels were recorded at a second Japanese nuclear facility, Onagawa, on Sunday, although authorities insisted the facility's three reactor units were "under control."

"It is considered to be extremely unlikely but the (nuclear) station blackout has been one of the great concerns for decades," said Ken Bergeron, a physicist who has worked on nuclear reactor accident simulation.

Nuclear opponent Ira Helfand, board member of Physicians for Social Responsibility, said an overlooked threat to nuclear plants is terrorism.

"They are essentially weapons of mass destruction that we build ourselves and site next to our cities and thereby hold huge numbers of people hostage to acts of nature or occasionally perhaps acts of man that we cannot control," he said.

The reactor problems in Japan are "obviously a significant setback for the so-called nuclear renaissance," in the United States, said Peter Bradford, a former NRC member. Bergeron, Helfand and Bradford spoke to reporters on Saturday.