TRENTON, N.J. (AP) -- Environmental and other watchdog groups in four states have filed a federal lawsuit to try to stop the U.S.  Army from trucking the byproduct of a deadly chemical weapon to New Jersey, where it would be treated and dumped into the Delaware River.

The complaint claims the Army's plan to transport the byproduct of neutralized VX nerve agent from Indiana violates a federal law banning interstate movement of chemical weapons.

The suit, filed in federal district court in Washington on Wednesday and made public by the plaintiffs Thursday, also challenges the Army's assessment of the impact the proposed project would have on the river. The complaint was filed by several groups including Delaware Riverkeeper Network and Chemical Weapons Working Group of Berea, Ky. It seeks to force the Army to complete an environmental impact statement before the project is allowed to move forward.

"We're challenging this toxic threat, and we're also challenging future toxic threats," said Delaware Riverkeeper Maya K. van Rossum. She said it's vital to stop the Army now because there are numerous chemical weapons stockpiles in need of disposal.

Tons of chemical weapons--including VX, mustard gas and sarin--are stored in bunkers at the Blue Grass Army Depot near Richmond, Ky.

A message left seeking comment from the Army was not immediately returned Thursday.

VX is so deadly that a single drop can kill a person in minutes by paralyzing their nervous system, causing suffocation. The Army is required by a 1997 international treaty to destroy the Cold War-era remnant by 2012 and is in the process of neutralizing its stockpile at Indiana's Newport Chemical Depot.

The Army has tried for years to win approval to ship the byproduct to a DuPont facility in Deepwater, where it would be treated and then discharged into the Delaware.

The proposed dumping site, near the Delaware Memorial Bridge, is 30 miles upriver of the Delaware Bay's oyster beds.

Environmentalists and officials in Delaware and New Jersey oppose the plan and have said they will fight it through legislation and in court, if necessary. Meanwhile, a federal review of the plan is continuing.

Co-plaintiffs in the suit are the American Littoral Society, Pennsylvania Clean Water Action, the Delaware and New Jersey Audubon societies and the New Jersey Environmental Federation.