Following months of criticism about security gaps at the nation's seaports, the Bush administration is requiring background checks for port workers to look for links to terrorism and ensure they are legal U.S. residents.

The heightened scrutiny — which will begin immediately — drew praise Tuesday from some lawmakers and port associations that said the checks were long overdue. Others jeered the security measures as either too weak or too invasive of workers' privacy rights.

Names of an estimated 400,000 employees who work in the most sensitive areas of ports will be matched against government terror watch lists and immigration databases, Homeland Security Secretary Michael Chertoff said. They will be among roughly 750,000 workers — including truckers and rail employees — who have unrestricted access to ports and will be required to carry tamper-resistant identification cards by next year.

"What this will do is it will elevate security at our ports themselves so that we can be sure that those who enter our ports to do business come for legitimate reasons and not in order to do us harm," Chertoff said. The background checks will not examine workers' criminal history, although Chertoff left open that possibility for the future.

How much the background checks will cost was not immediately available.

The Bush administration has been under fire for months for what critics call holes in security measures at ports, which were highlighted after a Dubai company's purchase of a British firm gave it control of six American ports. An outcry in Congress led the Dubai company, DP World, to decide to sell the U.S. operations to an American firm.

Congress is considering port security legislation this week, prompting some to question the sincerity and timing of Chertoff's announcement.

"It appears that DHS steps up to the plate to protect our national security only when the cameras are rolling and the whole world is watching," said Rep. Bennie G. Thompson, D-Miss., the top Democrat on the House Homeland Security Committee. He gave tepid praise for the push for ID cards, which he said should have been issued years ago.

In 2002, Congress ordered the Transportation Security Administration to issue biometric ID card to port workers who passed criminal background checks. Those cards were supposed to be issued to port workers beginning in August 2004. By that December, the Government Accountability Office said, bureaucratic delays and poor planning were hampering development of the card.

Cargo industry officials have worried that a federal ID system aimed at boosting security could cost many port workers their jobs — leading to bottlenecks in the flow of goods destined for virtually every U.S. community.

"It seems to us that the biggest security threat is coming from the outside, and not from the workers who live and work in those communities," said Steve Stallone, spokesman for the San Francisco-based International Longshore and Warehouse Union.

Still others questioned the wisdom of checking for terror links without also examining a worker's criminal history.

"While today's announcement is an important and necessary first step, criminal background checks must eventually become a part of the screening process," said Anthony Coscia, chairman of thePort Authority of New York and New Jersey.

Some workers already have their criminal backgrounds checked by local authorities, said Jim McNamara, spokesman for the International Longshoreman Union, which represents East Coast port workers and said it welcomed steps "to secure our ports in any way possible."

Since the DP World furor, Democrats have lambasted Homeland Security for failing to screen and inspect all cargo that enters the United States at seaports. Senate Democrats are pushing legislation to require Homeland Security to outline how it will scan all cargo containers within five years. The department currently inspects 6 percent of cargo containers that enter U.S. ports.

Homeland Security treats port security like a "neglected stepchild," said Sen. Charles Schumer, D-N.Y.

Chertoff said two-thirds of all containers will undergo radiation screening for nuclear materials by year's end and that 80 percent of cargo entering the United States comes from foreign ports with rigorous inspection standards. But he said it is impossible to physically inspect every cargo container without snarling port commerce.

"To call for all physical inspection of every container is like saying we're going to strip search everybody who gets on an airplane," he said.

Following months of criticism about security gaps at the nation's seaports, the Bush administration is requiring background checks for port workers to look for links to terrorism and ensure they are legal U.S. residents.

The heightened scrutiny — which will begin immediately — drew praise Tuesday from some lawmakers and port associations that said the checks were long overdue. Others jeered the security measures as either too weak or too invasive of workers' privacy rights.

Names of an estimated 400,000 employees who work in the most sensitive areas of ports will be matched against government terror watch lists and immigration databases, Homeland Security Secretary Michael Chertoff said. They will be among roughly 750,000 workers — including truckers and rail employees — who have unrestricted access to ports and will be required to carry tamper-resistant identification cards by next year.