The Buncefield oil fire, Britain’s biggest peacetime explosion, was the result of negligence by a duty supervisor at the depot, a High Court judge ruled yesterday.

Mr Justice David Steel made the ruling during a preliminary hearing of a case in which victims of the 2005 blast are suing Total and others for up to £1 billion in damages.

The court heard that Total and Hertfordshire Oil Storage Ltd (HOSL), a joint venture with Chevron, had previously conceded that negligence by someone was responsible for the huge fire at the Hertfordshire oil depot.

On Thursday, in a statement to The Times, Total UK said that the duty supervisor at the time was responsible for the explosion but it refused to admit either civil or criminal liability for the incident. Who controlled and employed the duty supervisor remains a live issue.

Total and Chevron are facing hundreds of compensation claims from individuals and local businesses. The court heard that the largest single claim was from Marks & Spencer, the high street retailer, whose sandwich business is located near Buncefield and was disrupted for several days after the explosion.

The negligence ruling is important because it means that the issue will not need to be argued when the case goes to a full hearing in October.

This is a small but significant early victory for the claimants, who include about 280 families whose properties were damaged or destroyed by the blast. However, compensation is far from guaranteed.

Although it admitted negligence by someone, Total UK intends to argue that it did not employ the duty supervisor. HOSL is also denying responsibility for his employment, and this will be a live issue at the hearing later this year. Both companies say they should not be liable for damages because they could not reasonably have foreseen that it would cause the destruction it did. Chevron also denies responsibility.

The fire began at the HOSL facility within the Buncefield compound at 6am on December 11, 2005. Forty-three people were injured. All 630 businesses on the nearby Maylands industrial estate were disrupted. Asos, the fashion retailer whose main warehouse is less than a mile from the Buncefield site, was forced to suspend its shares and halt internet sales because of the disruption.

Firefighters took 59 hours to extinguish the fire, in which 20 fuel containers were set alight. In addition to damage to local businesses and homes, about £10 million worth of fuel was destroyed. There was damage to housing in Dacorum and St Albans and about 2,000 people were moved from homes and businesses in Hemel Hempstead after the explosion, which could be heard up to 40 miles away.

A report in 2006 by an independent investigation board did not apportion blame, but found that human error and faulty safety equipment had been responsible.

To improve their chance of securing compensation, lawyers for the claimants asked the judge for permission to amend their case, adding an accusation of public nuisance to the existing charge of private nuisance. In a public nuisance case, pure economic loss is recoverable, whereas in a private nuisance claim, only damage from physical intrusion can be sought.

The new claim, which was admitted by the judge, gives the claimants another avenue of attack.

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