Defense Minister Jose Viegas said 16 employees were confirmed to have died in the blast that devastated the space center in Maranhao state Friday, while five more were missing and 20 others injured.

State security officials gave the toll as 19 dead.

The prototype rocket was being prepared to launch two Brazilian observation satellites into orbit on Monday when it exploded, virtually carbonizing the bodies of the victims and destroying the satellites.

The explosion was triggered when one of the rocket's four main thrust engines was unintentionally fired up. The platform on which the technicians were working disintegrated.

"Because it was impossible to identify the bodies, we were forced to hold a roll call of technicians," Viegas said.

Twenty-one workers did not respond and had not been located when rescue workers called off their efforts at around 8:00 pm (2300 GMT), officials said. The search was to resume on Saturday.

Viegas said an investigation would be carried out "with speed and efficacy"

to determine the cause of the blast.

"On behalf of the government I want to express deep regret over the death of these workers who were laboring in such a noble cause," he said.

The explosion marks the third failure in Brazil's attempt to become the first Latin American nation to launch a rocket into space. Rocket launches were aborted for technical reasons shortly after blast-off in 1997 and 1999.

Brazilian President Luiz Inacio Lula da Silva said he "deplored" the accident and "paid homage to the victims and their families," his spokesman said.

But he added that Brazil remained determined to pursue space technology.

Television images shot by an amateur cameraman from a nearby beach showed the rocket and pieces of the launcher disintegrating in the air. A blaze on the launch pad that followed the explosion was rapidly brought under control.

About 700 people worked at the base on a jungle peninsula on Brazil's Altantic coast.

About 220 people were working on the launch project. A much smaller team was on the launch platform at the time of the blast.

Globo Television, citing an Air Force officer, said that most of the victims were civilian technicians working on the rocket, three days before its scheduled launch.

The VLS rocket was the third prototype in a series, a spokesman with the Brazilian Space Agency said. The 50-tonne, 19 meter (62 foot) vehicle was designed to carry up to 40 tonnes of fuel and had cost about 6.5 million dollars (six million euros).

With an orbital range of 1,000 kilometers (600 miles), the rocket was to have given Brazil a long-sought entree into the world satellite launch market.

SPACE.WIRE