£9.5m bill for firms behind Britain's most costly industrial disaster.

Five companies have been ordered to pay £9.5 million for their part in the 2005 fire and explosion at the Buncefield Oil Storage Depot, in Hertfordshire.

The £1.3 million in fines for the pollution caused are a record in the UK.

Concluding a four-month trial at St Albans Crown Court, Mr Justice Calvert-Smith said the companies had shown "a slackness, inefficiency and a more or less complacent attitude to safety."

The prosecution of Total UK Ltd, British Pipeline Agency Ltd (BPA), Hertfordshire Oil Storage Ltd (HOSL), TAV Engineering Ltd (TAV) and Motherwell Control Systems 2003 Ltd, followed the most complex investigation ever conducted by the Health and Safety Executive and Environment Agency.

The painstaking investigation uncovered a series of serious failings that led to thousands of gallons of petrol being released in a large vapour cloud.

The resulting explosion registered at 2.4 on the Richter scale, injured 43 people, and destroyed nearby businesses. The environmental impacts of the disaster are still evident today.

The cost of dealing with the disaster has been estimated at more than £1billion, making it the most costly industrial incident in the UK.

Kevin Myers, HSE's Deputy Chief Executive, said:

"Incidents like the explosion at Buncefield are exceptionally rare. However, society rightly demands the highest of standards from the high hazard industries. Businesses in this sector must manage the risks they create effectively because when things go wrong, the consequences are severe and can destroy lives and shatter local communities.

"Major hazard industries must learn the lessons of events like this. From the Board room down companies must ask themselves these questions: do we understand what could go wrong; do we know what our systems are to prevent this happening; and are we getting the right information to assure us they are working effectively."

Howard Davidson, Thames Director at the Environment Agency, said:

"As a result of a successful investigation and prosecution, five companies have today been held to account for their failures.

"The Buncefield blast shattered the local community and left a long-term legacy of pollution. It has already involved a five-year clean up operation by the oil companies involved and the Environment Agency will be a presence around the site for many years to come.

"There should be no doubt that we will always seek to prosecute those who cause serious pollution and damage the environment for future generations"

The following sentences were handed down:

• Oil giant Total UK Limited pleaded guilty to three offences and was fined £3.6 million (£3million for safety; £600,000 for pollution) and ordered to pay costs of £2.6 million
• Supply company British Pipeline Agency Ltd pleaded guilty to two offences and was fined £300,000 for environmental offences and ordered to pay costs of £480,000
• Hertfordshire Oil Storage Ltd was found guilty of two offences and fined £1.4 million (£1million for safety; £450,000 for pollution) with costs of £1 million
• TAV Engineering Ltd, which designed a crucial safety switch that failed, was found guilty of one offence, fined £1,000 and ordered to pay £500 costs
• Installation and maintenance company Motherwell Control Systems 2003 Ltd fined £1,000 and ordered to pay costs of £500 after being found guilty of one offence