A postal union said Friday that it will sue the Postal Service to shut down a huge Manhattan mail processing plant where four machines have been contaminated with anthrax.

"Close the facility, test the people, clean it up and send people back when it's safe," said Louis Nikolaidis, attorney for the New York chapter of the American Postal Workers Union.

He said he has notified the Postmaster General's office of the intent to sue and would take the case to federal court if the Morgan Processing and Distribution Center remains open to its 5,000 employees.

The nation's anthrax outbreak has killed three people since Oct. 5, including two Washington postal workers this week. Nikolaidis said the lawsuit would be based on federal law governing transportation of hazardous material.

"It's time for the Postal Service to start putting workers first," union local President William Smith said. "They want the workers of New York Metro to be guinea pigs and I'm not going to stand for that foolishness."

The Postal Service, citing the advice of health officials, has said there is no need to close the plant, which handles all mail for Manhattan and the Bronx -- about 20 million pieces of mail a day. Spokesman Dan Quinn said he could not comment on the lawsuit.

At the Maryland funeral for one of the Washington anthrax victims, the union's president-elect William Burrus told the postmaster general that postal workers would not work inside any contaminated facility.

"I'm not placing blame, but we don't want to make that mistake again," he said.

The postal workers' union and the National Association of Letter Carriers represent some 600,000 employees who process and deliver mail across the country.

The Postal Service disclosed the anthrax contamination at the Morgan facility Thursday. The four machines may have been tainted by anthrax-laced letters sent to NBC and the New York Post from Trenton, N.J., but no source has been determined.

Tony Musso, a Postal Service spokesman, said the facility is not used by the public, and "the public need not be concerned about mail they receive."

Smith said the Postal Service will allow Morgan employees to work elsewhere in the system without losing pay. He urged his members to do so but said the Postal Service should go further.

"If it's possible to close down Congress and test there for bacteria, they should close down this building too," he said. "I do believe that taking the time is more important than taking people's lives."

Quinn said Friday that absenteeism was no higher than the normal 6 percent to 7 percent. But one worker coming off a midnight-to 8:30 a.m. shift at Morgan said several colleagues didn't show up.

"There's a lot missing from all floors," said Keith Kirk, a machine clerk. And "the crew that just came in looks like a skeleton crew."

Postal officials have cordoned off the sorting machines, saying they would be cleaned after further testing. Kirk, who carried a breathing mask, said the machines were surrounded with bright-orange tape Friday but had not yet been cleaned, a concern to many workers on the third floor. He said he was trying not to think about anthrax.

"I try not to let it bother me," he said. "I just remember I'm coming here for the overtime."

Others workers objected strongly.

"I think management finds it cheaper to possibly pay sick benefits or death benefits rather than to close the building and decontaminate it," said Bill Bachmann, 51, an electronic technician.

"People are scared," he said.

No postal employees have tested positive for anthrax in New York, but the Postal Service has made the antibiotic Cipro available to 7,000 workers at Morgan and five other postal facilities in New York. More than 1,100 had received the drug by Thursday afternoon.

Four people -- one each linked to NBC, the Post, CBS and ABC -- have confirmed cases of cutaneous anthrax, which is far less dangerous than the inhaled form of the disease blamed for the three deaths.

City health officials say a second case at NBC, stemming from the same letter that is believed to have infected an assistant to news anchor Tom Brokaw, is probably skin anthrax.

The victim's name was not made public but NBC said she was a desk assistant who handled the letter.

"The woman is fine," said spokeswoman Kassie Canter.