The cause of a huge blaze which ripped through a motor business workshop yesterday morning may never be known, fire investigators said last night.

The damage caused by the fire at David Jones Cars, on the edge of Downham Market, was 'too severe' for investigation officers to establish a cause.

But neither the fire service or police are treating the blaze as suspicious.

Around 90 firefighters from Norfolk and Cambridgeshire were called to the St Johns estate when the fire broke out at the business at around 3.20am.

The A1122 was then closed between Hythe Bridge and the junction of the B1507 Downham Road by police officers for more than five hours as fire crews tackled the blaze.

Station manager Bob Ayers, of King's Lynn, said the crews faced a difficult job and because of the way the buildings were constructed, they fought the fire from the outside.

'We did not commit any crews into the workshop itself. At one point the crews were withdrawn because we thought there were acetylene bottles inside. Once we knew that wasn't the case, we carried on,' he said.

A total of 12 crews from Downham Market, King's Lynn, Methwold, West Walton, Outwell, Wisbech and Terrington were all called to the scene.

Mr Ayers said two vehicles inside the main workshop were damaged by the blaze, but several vehicles were moved to safety by officers and the adjoining office, which contained computers and paperwork, was also saved.

A Norfolk Fire and Rescue spokesman last night added: 'The fire investigation officers' conclusion is, on this occasion, simply too severe for us to be able to establish a cause so the cause is unknown.'

Meanwhile businesses on the industrial estate around David Jones Cars offered their support and sympathy to the owner of the company.

Neil Attwell, owner of Advanced Water Treatment, said: 'I've only saw the burnt out shell as I drove past to get here but it looked pretty bad.

'He's a nice bloke and it's terrible timing with Christmas just around the corner.'

He continued: 'We are quite a close-knit business community here and we all look out for one another.

'I wouldn't want to see that happen to anyone because I know how tough business is for everyone and I don't want to see anyone struggling.'

Chris Peach, owner of Oz-UK, a steel building firm, added: 'It's terrible news for him. He must be devastated.'