Updated

Many people at U.N. headquarters worry about security risks and exposure to toxic asbestos during the upcoming renovation of the 60-year-old New York skyscraper, its staff union chief said on Thursday.

The $2 billion renovation project is intended to make the blue-green tinted 40-story building along Manhattan's East River safer, more comfortable and greener.

During the renovation, which is already underway and is expected to take several years, U.N. employees, contractors and accredited media representatives will be moved to temporary office spaces inside or near the U.N. complex.

Stephen Kisambira, president of the United Nations staff union, held a rare news conference at U.N. headquarters to voice staff concerns about the so-called Capital Master Plan.

"Asbestos abatement is a serious issue," he told reporters. "The risk is there ... They are saying that nothing can go wrong. How can they be sure?"

Removal of the cancer-causing flame-retardant asbestos lining the ceiling tiles of the U.N. building is one of the most sensitive aspects of the renovation.

The project's manager, New York architect Michael Adlerstein, has assured U.N. staff that there is nothing to worry about. His office has set up a Web site that explains various aspects of the renovation, including asbestos.

"There are very stringent requirements for asbestos procedures, and those will be followed by the contractors," the website says. But Kisambira is not convinced.

One of the problems, he said, was that contractors removing the asbestos cannot be sued because of the special legal status of the United Nations, which is technically not U.S. territory. Because of the lack of liability, he said, many staff are worried that the contractors will be less careful than usual.

Neither Adlerstein, his spokesman nor the construction manager, Skanska USA Building, were available for comment.

'VULNERABLE TO ATTACKS'

Kisambira said that the problem of asbestos in the U.N. building is not a new one. He said New York City authorities were permitted to take air samples in the building several years ago but their findings were never released.

He also complained that U.N. Secretary-General Ban Ki-moon and his administration have not carried out a threat and risk assessment for most of the U.N. structures, including the temporary ones where workers will be housed for several years.

"The organization's vulnerable to attacks, everywhere," Kisambira said. "We need to know what risks we are facing."

The staff union has adopted several resolutions demanding a risk assessment, but those have been ignored, he said.

Although the main U.N. facilities in the United States, Vienna and Geneva are widely considered to be secure, there have been high-profile attacks on U.N. buildings elsewhere, prompting a tightening of security at U.N. sites worldwide.

In December 2007, a car bombing at the U.N. building in Algiers killed at least 41 people, among them 17 U.N. staff. In 2003, 15 staff and seven others were killed by a bomb attack at the U.N. building in Baghdad.