The world’s biggest chemical company BASF says it believes two of its employees died in an explosion at a plant in Germany.

Six people were severely injured and two people are still missing, the company said.

The blast happened at the Ludwigshafen site on the river Rhine about 50 kilometres south of Frankfurt.

It’s the company’s headquarters and the world’s largest chemical complex.

The explosion was preceded by a fire in a pipeline between an area where liquids are stored and storage tanks.

The blast happened after the company’s fire service arrived.

Several facilities near the blast site were shut down for safety reasons.

The authorities advised people in the surrounding area to avoid going outside but there was said to be no danger to the population.

A separate earlier blast at another BASF site in Germany injured four people.

The company is investigating what caused both explosions.