A fierce blaze in a metal fabrication unit caused traffic chaos on Friday afternoon as police sealed off all entrances to Great Yarmouth's Harfrey's Industrial Estate.

Neighbouring businesses were evacuated as police set up a 200m exclusion zone around Cap Fabrications, on the estate's Faraday Road, because of concerns that potentially explosive oxy-acetylene cyliners were present.

At the height of the blaze about 60 firefighters were battling to control it and 13 fire engines were called in from as far away as Norwich.

There was major traffic congestion on the A12 and traffic slowed on all routes into and out of Yarmouth.

Norfolk Fire Service group manager James Belcher said: 'When firefighters arrived on the scene at about 1pm they found a rapidly developing fire but successfully employed aggressive fire-fighting techniques to stop it spreading.

'There was a large pall of smoke visible from all parts of Yarmouth and that prompted loads of calls to our control room.'

He said it was initally feared gas cylinders were on the premises which could expand and explode in the heat so a 200m exclusion zone was set up with the help of police.

By 3pm, the fire was under control and water jets were being used to put it out. As soon as it was out, fire investigaters would go in to look for the cause, he added.

Insp Gary Crowther said more than 40 officers were involved in setting up the exclusion zone and the evacuation of business premises over a large area.

'By 3pm we were relaxing the exclusion zone and allowing people back to their offices to pick up their personal possessions. A lot were then going home early,' he said.

Trevor Chilvers, a director of Independent Lifting, a lifting equipment maker next door to Cap Fabrications, said: 'I was in my office when one of our workers came in and said,'we had better get out, there's a major fire'.

'Black smoke was billowing out of the unit and then flames started coming out of the top of the building. We were worried it would spread to our unit.'

It is understood Cap Fabrication employs at least 20 people; staff were looking on as firefighters battled the blaze but were too upset to talk about it.