Lord Browne of Madingley, the chief executive of BP, faces courtroom questioning over the deaths of 15 workers and hundreds of injuries caused by the Texas City refinery explosion.

The UK oil group has fought to keep its chief executive out of the case, but a Houston appeals court ruled late on Friday that he must appear to answer plaintiffs’ questions.

The case is the first of more than 170 lodged by those who claim that they were injured in the March 2005 accident. BP has settled with the families of all those killed.

The company has accepted responsibility for the accident, but has been fiercely rebuked by regulators and an independent inquiry after it was shown that cuts led to lapses in safety procedures that could have prevented it.

BP has long opposed putting its outgoing chief executive in the witness box and would not say last night whether it would continue to fight his court appearance. A BP spokesman in Houston said: “We are weighing our options. The decision was made on Friday night and we have yet to decide our next move.

“As we have said before, Lord Browne has no unique knowledge of the events that led up to the explosion so we do not necessarily agree that he would make an appropriate witness.”

The spokesman said defence lawyers had been given access to every senior BP person in its refinery business in the US.

Brent Coon, a lawyer for one of the plaintiffs, said that the court’s decision marked a big boost for his case.

“The ruling is unique in that it is rare for the chief executive officer of a major company to be forced to testify against his will, lending further support to our long-standing contention that Lord Browne was directly involved in decision-making roles that contributed to this horrible tragedy,” Mr Coon said.

“Hopefully his deposition will shed further light on the full extent of his knowledge.”

The spokesman for BP, which has set aside $1.6 billion (£820 million) to settle personal injury cases related to the explosion, said that the company would continue in its efforts to make fair payments to all those who warranted them.

“We do not want to see any case go to trial that does not have to go to trial,” the spokesman said. “It has been the company’s intention all along to make sure that those who were hurt by events at Texas City are fairly compensated.”

Lord Browne, who is said to be angered by the court’s decision, is to retire in July and will be succeeded by Tony Hayward, BP's head of production and exploration.

If he gives evidence, Lord Browne is expected to be questioned closely about the cost-cutting regime that led to record returns for the oil giant but which have been shown to have reduced spending on safety issues.

The Local Authority Pension Fund Forum, which controls £70 billion of assets and has £700 million invested in BP, has demanded that BP effect stronger controls on remuneration and internal investigations after a series of safety failures. On Friday the London Pension Funds Authority began US litigation to try to freeze an estimated £72 million package for Lord Browne of Madingley, BP’s outgoing chief executive.

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