About 300 gallons of caustic wastewater, a byproduct from the destruction of Cold War-era VX nerve agent, spilled at the U.S. Army's Newport Chemical Depot on Tuesday, the fourth spill since operations began in May.

No injuries were reported.

The wastewater -- what's left after the banned chemical warfare agent is neutralized by mixing it with hot sodium hydroxide and water -- contained no live agent, said Newport spokeswoman Terry Arthur.

The leak occurred just after 2:30 p.m. in a contained area where VX is destroyed in large reactors. Two maintenance workers in protective suits were in the cubicle, but the cause of the spill was unknown.

"The good news is, no one was injured, there was no danger to workers or the public, and the response was very quick," Arthur said.

VX, manufactured in Newport in the 1960s as a deterrent to Soviet aggression, is so lethal that one drop could kill a person in minutes. It was manufactured only in Newport, in Vermillion County near the Illinois border, but never used by the United States.

About 250,000 gallons of the chemical have been stored in 1-ton steel containers at Newport since production ceased in 1969. About 33,766 gallons have been destroyed in the past 10 months by an Army contractor.

VX destruction will be halted until the spill is cleaned up and its cause determined, Arthur said.

Previous spills occurred in June, July and October. The largest was Oct. 28, when 500 gallons of byproduct leaked as a result of faulty gaskets.

Work also was stopped most of last summer after spills in June and July that were blamed on faulty valves and after it was discovered that the byproduct was more flammable than thought.

The destruction of the VX is scheduled to be complete by November 2007.