Citing a need to keep information from terrorists, regulators said Wednesday the government will no longer reveal security gaps discovered at nuclear power plants or the subsequent enforcement actions taken against plant operators.

The Nuclear Regulatory Commission (search) announced the change in policy during its first public meeting on power plant safety since the Sept. 11, 2001, terrorist attacks. It drew barbs from critics who said the secrecy would erode public confidence in the agency.

Until now, the NRC has provided regular public updates on vulnerabilities its inspectors found at the country's 103 nuclear power reactors, such as broken fences or weaknesses in training programs.

"We need to blacken some of our processes so that our adversaries won't have that information," said Roy Zimmerman, director of the commission's Office of Nuclear Security and Incident Response (search), which was created after the attacks.

NRC spokesman Scott Burnell said commissioners voted to take the step March 29, but kept it quiet as agency staff worked to implement the plan. The vote itself was revealed Wednesday and had nothing to do with this week's warnings that terrorists had surveyed U.S. financial institutions, Burnell said.

"We deliberated for many months on finding the balance between the NRC's commitment to openness and the concern that sensitive information might be misused by those who wish us harm," commission Chairman Nils Diaz said in a written statement.

Michele Boyd, a lobbyist for the consumer group Public Citizen (search), said the NRC had not struck that balance.

"The public has zero confidence in NRC and making this information completely out of the public, not available, does not bring any more confidence," Boyd told the commission.

Rep. Ed Markey, D-Mass., a longtime critic of the nuclear industry, said the policy will "further deepen public skepticism of the commission's performance and calls into question whether the commission is doing what it must do to keep nuclear reactors safe from terrorist attacks."

Zimmerman of the NRC said the agency is considering providing general information on security vulnerabilities that would not include plant names or other details.

Protection at the nation's nuclear power reactors — located at 64 sites in 31 states — has been boosted since the Sept. 11 attacks. Since then, the commission has been guarded about revealing specifics of the security efforts.

That has not stopped accusations of inadequate guard training and other security lapses.

Congressional investigations have found problems such as a guard falling asleep on the job and falsification of security logs. Reports from the Energy Department's inspector general noted other problems at sites run by that agency, such as guards being warned of upcoming security exercises and inconsistent training from site to site.

Nuclear activists expressed concerns at the meeting about the adequacy of guard training, fire protection, the security of pools containing spent nuclear fuel, and planning for different kinds of attacks.

They also raised concerns about the agency's plans to allow the security firm Wackenhut Corp. to run mock terrorist attacks on the plants, nearly half of which are protected by Wackenhut security guards.

"When you have Wackenhut test Wackenhut, nobody is going to believe those results," said Peter Stockton, senior investigator with the Project on Government Oversight (search), a research group.

NRC's Zimmerman said the agency would closely monitor the exercises to make sure no information about the timing or methods of the mock attacks is leaked to plant personnel.

In the weeks after the Sept. 11 attacks, operators at the nation's nuclear power plants posted more guards, added security patrols and reduced access to the installations' most sensitive areas.

Military planes at nearby bases stood ready to intercept any suspicious aircraft; the Coast Guard patrolled the Great Lakes near power plants to keep ships away; and many facilities enlisted the help of National Guard troops.

Some critics say more needs to be done.

"The vulnerabilities at a lot of the reactors in this country have not been addressed," said Jim Riccio, a nuclear policy analyst for Greenpeace (search). "Here we are nearly three years from the attacks and I don't see anything they've done except extending the perimeters of these facilities."

NRC spokesman Eliot Brenner disputed that assessment, saying the agency has aggressively pushed plant owners to, among other things, sharply upgrade security programs and training; conduct more realistic tests of plant defenses; and communicate better with the intelligence community, law enforcement and emergency response agencies.

The energy sector contributed $3.7 million, more than half of which came directly from nuclear and electric power companies, to Democrats during the 2004 election cycle. Republicans got $9.2 million from energy sources, including $2.7 million from power companies.