DENVER (AP) -- Colorado health officials say officials at the Pueblo Chemical Weapons Depot near Pueblo aren't doing enough to ensure the safety of its workers, the environment or people living near where thousands of tons of deadly mustard agent are stored.

Documents filed Tuesday in a lawsuit pending in U.S. District Court ask a judge to order the depot to increase the frequency and sensitivity of air monitoring at the facility.

The Colorado Department of Public Health and Environment is concerned over unplanned releases of mustard agent from artillery shells stored in 94 igloo-like structures at the site. The weapons, banned by international treaty, are being stored there until they can be destroyed.

Depot spokesman Chuck Sprague says their monitoring operations are safe.

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