Firefighters are still at the scene this morning of a major factory fire near North Walsham.

The blaze, which broke out yesterday teatime in an industrial fryer at Heinz Frozen and Chilled Foods, had been contained by about 9pm but flared up again around midnight.

The factory, on Station Road, Westwick, which employs about 200 people, remained closed this morning.

Fire chiefs were awaiting the arrival of a structural engineer and the plant's director to discuss partial dismantling of the building housing the fryers in order to reach the seat of the fire.

Earlier this morning David Ashworth, group manager with Norfolk Fire and Rescue Service, said that the blaze was under control a second time but crews had faced a very difficult job because of the 'sandwich panel' construction of the building.

It was made from two thin sheets of plastic-coated steel with a 'filling' of highly-combustible polyurethane foam.

Mr Ashworth said such buildings were widely used throughout the food industry because they were easily cleaned but the fire had spread to the polyurethane core where it was deep-seated and extremely difficult to access.

At one point last night around 90 firefighters from 10 stations were at the scene and black smoke billowed across surrounding homes and countryside.

Crews used aerial ladders to direct foam at the building but thermal imaging cameras had revealed a rise in temperature at about midnight and the flames had become more visible, according to Mr Ashworth who said extra resources had then been brought in.

'The fire has been brought under control but there are still hot spots,' he said this morning.

Four engines and a control unit were still on the scene at 6am.

Mr Ashworth praised the 'skill and tenacity' of firefighters throughout the incident and said Heinz staff had been 'very co-operative and supportive.'

He added: 'The crews worked very well in difficult circumstances and we are heading towards a successful outcome.'

It is believed that 50 to 60 people were on the site when the blaze broke out but the buildings were safely evacuated and there were no casualties.

An investigation into the fire was also due to get underway this morning.

The factory processes potato products including Aunt Bessie's Roast Potatoes, Aunt Bessie's chips, wedges and croquettes, and Mid -Week Mini Roasties.