The deployment comes as government officials and the public have become concerned about the safety of the nation's 103 nuclear power plants in the wake of the Sept 11. hijacked plane attacks on New York and Washington.

As a precaution, the U.S. Nuclear Regulatory Commission has temporarily shut down its Web site to review its contents and remove anything that might prove a safety risk. New Jersey has also ordered National Guardsmen to protect its reactors.

But other states have yet to deploy troops at their reactors, experts said, warning that a successful attack on a plant could kill thousands and spread radioactive contamination over hundreds of miles (km).

Steve Dolley, the research director at the Nuclear Control Institute, a research center specializing in problems of nuclear proliferation and safety, said such an attack could come from a hijacked airplane, a truck bomb or a "commando style raid."

"It's very difficult to determine how safe these plants are right now, based on information in the public domain," he said, adding "we hope that governors in other states will take similar measures."

New York's troop deployment was not connected to any specific threat. But given "general threats being made by terrorist groups, it is a prudent action to augment and enhance the high level of security that is currently being maintained," Pataki said.

At the Indian Point nuclear plant, located about 20 miles (32 km) north of New York City on the Hudson River, the troops come in addition to a series of security measures taken since last month's hijacked airplane attacks on the United States.

Jim Steets, a spokesman for Entergy Corp. which owns the Indian Point plant, would not comment on details of the additional security.

But he said, "Imagine every possible way you can get into this plant, as authorized personnel, a visitor, a member of the media, and understand that every way you could have gotten into the plant in the past has changed."

Along with Indian Point Nuclear Power Plant Reactors 2 and 3, troops are stationed at Nine Mile 1 and 2 Nuclear Power Plants, the James A. Fitzpatrick Nuclear Power Plant and Ginna Nuclear Power Plant.