Amuay Explosion
Fire is seen after an explosion at Amuay oil refinery in Punto Fijo in Venezuela on Saturday. REUTERS/Hector Silva

With casualties of the earthshaking explosion at Venezuela's largest oil refinery rising to 39 dead and more than 80 injured on Saturday, President Hugo Chavez has called for an investigation to determine the cause of the firestorm at the Amuay plant in Falcon state in the northwest of the country.

Chavez also declared three days of national mourning, BBC News reported.

Earlier, Energy Minister Rafael Ramirez said the conflagration had been caused by a gas leak, according to El Universal in the capital city of Caracas.

Amuay and a neighboring facility form part of the Paraguana Refining Center, the second-biggest refinery complex in the world, with an overall capacity of 955,000 barrels per day, Reuters said.

The accident brought operations at the Amuay refinery to a screeching halt, but Ramirez told Reuters he anticipated production would be resumed by Monday. He also said Venezuela should be able to continue its fuel exports without interruption, which indicates the mishap may have little or no effect on energy prices.

According to BBC News, 18 of those killed in the blast were members of the National Guard stationed at the plant, 15 were civilians, and six are unidentified.