Some 20 people were also injured in the blast, the Globo television network reported, citing a security official for Maranhao state. A fire that followed the blast at the launch pad has been brought under control, it added.

The aeronautics command had a launch of the vehicle scheduled for August 25.

"Up to now the information that we have is that 16 people have died," a ministry spokesperson told AFP.

According to television newscasts, as many as 20 people may have died in the accident.

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

The cause of the explosion is still unknown, as well as the official number of people injured.

SPACE.WIRE