Thirty insurance companies have filed a multimillion-dollar lawsuit against Pacific Engineering and Production Co. and several of its suppliers and clients as a result of the May 4 blast that leveled the Henderson, Nev., ammonium perchlorate plant.

The insurance companies are seeking repayment of more than $50 million they paid for damages resulting from the earthquake-force explosion that destroyed the plant, killed two people, injured hundreds more and caused an estimated $73 million in property damage in the Las Vegas valley.Since the blast, PEPCON officials have decided to relocate the ammonium perchlorate production facility to a site near Cedar City, Utah.

The 26-page legal document filed Friday names American Pacific Corp., the parent corporation of PEPCON, Clark County, Nev., Morton-Thiokol Inc., Aerojet General Corp., and United Technologies Corp. as defendants.

The suit contends the company was negligent and reckless in its manufacturing process, safety control procedures and storage of ammonium perchlorate, an oxidizing agent of solid rocket fuel.

Morton-Thiokol, Aerojet General and United Technologies were all purchasers of ammonium perchlorate for solid-fuel rocket motors, and the suit contends the companies authorized its storage at the PEPCON facility on Gibson Road in Henderson.

The three companies should have ensured the hazardous material was being stored properly, the suit says.

Also named in the suit are Hoover Universal Inc. and Russell-Stanley Inc., manufacturers and suppliers of drums in which the ammonium perchlorate was stored.

The insurance companies also identified Clark County as a defendant and accused county officials of negligence for failing to inspect the facility and enforce safety regulations there.

PEPCON president Fred D. Gibson as well as Keith Rooker, James J. Peveler, Jack Cooper, Norval F. Pohl, Thomas A. Turner, W-J Carroll and Thomas L. War, who are officers and directors of the corporation, also were named as defendants.

Destruction of the plant has caused a critical national shortage of ammonium perchlorate - a chemical vital to the nation's space and defense programs.