Southwest Gas Company officials say their investigations have disclosed that natural gas was not the cause of the May 4 explosions that leveled the Pacific Engineering and Production Co. plant in Henderson, Nev.

Company officials, in a news release, said exhaustive tests conducted over the last month show there were no leaks in natural gas lines at or near the plant."When you look at the fact that our natural gas lines held pressure after the terrible explosions and during these rigorous tests, together with the other evidence we've collected, you see convincing proof that Southwest's facilities were victims of the explosions - not the cause. That's what we've been saying all along," said Southwest Gas President Kenny Guinn.

PEPCON officials have maintained that a leak in natural gas lines caused the explosions that killed two plant workers, injured scores of others and caused millions of dollars worth of property damage in the Las Vegas valley.

Last month, PEPCON officials announced they will move their ammonium perchlorate manufacturing operation to a site outside Cedar City.