The rocket was due to take two satellites into space next Monday from the Alcantara Space Center in the northeastern state of Maranhao.

Defense Minister Jose Vieigas Filho gave the official toll of 16 dead and said the rocket exploded at about 1:30 pm (1630 GMT). He said the toll was only based on "initial information".

Television reports said 19 or 20 people may have died in the accident.

Globo News television cited a Maranhao state security official as saying 20 people were injured in the blast.

Television images showed pieces of the rocket launcher disintegrating in the air. A blaze on the launch pad that followed the explosion had been brought under control, reports added.

A defense ministry statement said the dead had been working on the launch platform. About 700 people worked at the base which is in the jungle on a peninsula jutting into the Atlantic Ocean.

Vieigas, who was to visit the site on Saturday, said: "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."

President Luiz Inacio Lula da Silva was being kept informed of events, he added.

An inquiry to "rigorously and swiftly" determine the cause of the incident has been launched, he said.

The aeronautics command was scheduled to launch the vehicle on August 25.

Globo, citing an Air Force officer, said that most of the victims were civilian technicians working at the space center.

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

The vehicle is one of the most simple of its type, with an orbital range of 1,000 kilometers (600 miles).

SPACE.WIRE