The death toll from the explosion this weekend at the Amuay oil refinery in the northwestern Venezuelan state of Falcon has risen to 39, the government said.

The Amuay refinery is one of three that make up the Paraguana Refinery Complex, or CRP, the largest in this South American country and one of the largest in the world.

Workers clearing the rubble from Saturday's blast found "new corpses," Vice President Elias Jaua told state television.

"Up to this moment, of the figure of 39 (people) who are in the social security hospital morgue, 18 of them are already acknowledged to be members of the Bolivarian National Guard," Jaua said.

Fifteen of the victims are civilians and, mainly, relatives of the soldiers who were in the houses of the 45th Detachment of the National Guard, a military complex with residential infrastructure, Jaua said.

"There are six corpses still to be identified," the vice president said.

Twelve injured people are being treated in different hospitals in the city of Punto Fijo, located 528 kilometers (328 miles) west of Caracas, where the refinery is located, and another nine injured were transported to the western city of Maracaibo, Jaua said.

A total of 86 people had to be given some kind of medical attention, many of them for burns, although the majority of them have already been released, Jaua said.

Oil and Mining Minister Rafael Ramirez said the blast was the result of a gas leak that formed a "cloud" and exploded at 1:11 a.m., producing a huge shock wave that damaged homes in the surrounding area along with a National Guard facility.

Ramirez said that the explosion "caused severe damage to National Guard Outpost 45" and blasted a part of the storage-tank area, causing a huge fire that burned all day.

"In the end we had nine storage tanks hit by the explosion," the minister said, adding that when the fatal cloud was detected the alarm was sounded, but it all happened "too fast" and the explosion was "almost immediate."

Jaua said that 209 houses and 11 local businesses had been damaged and that 13 families "had their homes completely destroyed" and were transported to the Punto Fijo naval base to be housed in the meantime.

The vice president said that the existing contingency plan was activated "to control the fire," admitting that firefighters have not been able to extinguish it but saying they will continue "battling all during the night" to do so.

After the incident, Venezuelan President Hugo Chavez ordered a "thorough" investigation of the matter and decreed three days of national mourning for the victims.

CRP manager Jesus Luongo on Sunday denied that the blast had occurred due to lack of maintenance, adding that some $6 billion had been invested in the refinery complex over the past three years.

Meanwhile, the general secretary of the Futpv petroleum workers union, Ivan Freites, accused the government of neglecting maintenance work in the oil industry in recent years. EFE