The U.S. Army and a contractor were fined nearly $52,000 for releasing a deadly chemical weapon on a wildlife sanctuary in the Pacific Ocean, federal environmental officials announced Wednesday.

An unknown quantity of VX nerve agent (search) was released in August 2002 at a chemical weapons disposal facility on Johnston Atoll (search), the Environmental Protection Agency's (search) office in San Francisco said. The release occurred when a tray holding remnants of a VX shell was improperly loaded into an incinerator.

Exposure to the agent can cause paralysis and death within minutes, but there were no known exposures or reports of harm to any person or any wildlife, said Dean Higuchi of the EPA.

The atoll, located 825 miles southwest of Honolulu, is a national a bird sanctuary. It also held more than 6 percent of the nation's stockpile of chemical weapons (search) — 412,000 different types of explosives, mustard and nerve agents. Congress ordered the weapons destroyed in 1986.

Disposal began in 1990 at a facility jointly operated by the Army and its contractor, Washington Group International (search) of Boise, Idaho. Neither the Army nor Washington Group admitted wrongdoing as part of the fine.

The Army had agreed to pay nearly $400,000 for previous violations in 1994 and 2000 involving VX and sarin gas.

More than 4 million pounds of chemical weapons and agents have been destroyed on Johnston Atoll since 1990. The Army has dismantled the facility and is in the process of restoring the site to its natural role as a wildlife refuge.