The recent death of a worker at a refinery run by BP, the British oil group, in Texas City is to be formally examined by US federal investigators.

The inquiry is a setback for the oil company, which has been trying to improve its safety record after a string of American refinery incidents.

The death of William Joe Garcia, an operations supervisor with 32 years’ experience, occurred last month and was the third fatality at the refinery since a huge blast nearly three years ago that claimed 15 lives. Late last year BP paid $370 million (£188 million) in fines related to the deaths in 2005.

Mr Garcia was killed after a metal lid blew off a pressurised water filtration unit and hit him as he prepared to put the unit back into service.

The CSB, a federal agency charged with investigating chemical plant accidents, had been conducting a preliminary study since the accident. Yesterday Don Holmstrom, the lead investigator, said that there were now grounds for a full-scale inquiry.

Mr Holmstrom said that one focus of the investigation would be what led to the unexpected build-up of pressure under the lid. He said that the force that blew off the 500lb top was “well in excess of the normal operating pressure”.

A possible explanation is that explosive hydrocarbons or other chemicals were in the water running through the filter, Mr Holmstrom said. “Witnesses reported the water as being black,” he said.

However, some other malfunction on the unit may have been the cause, he added.

A BP spokesman said that the company would continue to cooperate with investigators. He said: “They’ve been on site for more than two weeks and we’ve been cooperating with them and we plan to continue to do so.”

Tony Buzbee, lawyer for Mr Garcia’s family, said that a full investigation of the Texas City refinery’s problems was needed, given 478 spills or releases reported to pollution regulators since 2000. “There’s a major problem with the plant at Texas City,” he said.

Explore Industry Sectors

• Banking & Finance

• Construction & Property

• Consumer Goods

• Engineering

• Health

• Industrials

• Leisure

• Media

• Natural Resources

• Retailing

• Support Services

• Technology

• Telecoms

• Transport

• Utilities

Times Recommends

• B&B shareholders forced into funding rescue
• John Lewis department store sales plunge 8.3%
• Families turn to credit to cover mortgage bills