People here are in shock and disbelief that anyone would want to destroy it

Cathedral chief executive Roy Bentham

Lincolnshire Police have gathered forensic evidence from the scene of the blaze, which happened at 1800 GMT on Tuesday.

They are appealing to the public for information.

A spokeswoman said: "Our enquiries are concentrated on two young boys, aged 10 to 12, who were in the cathedral about half an hour before the incident.

"They were spoken to by several members of staff, and beforehand by nearby shopowners.

"They have mid-brown hair and the younger one has an ear stud.

Candles set alight the altar cloth

"They may or may not be involved in the arson attack but we need to trace them."

Chief executive of Lincoln Cathedral Roy Bentham said the cost of protection against future attacks will be a lot higher.

He said: "This has opened our eyes to the very real possibility that someone could walk into the cathedral and deliberately burn it down.

"We need CCTV in areas of the cathedral traditionally seen as risk-free, such as the chapel and the nave.

"We also need to extend our fire alarm systems and replace our 2,500 plastic chairs with fire-resistant seating.

'European treasure'

"Some would say �250,000 is a modest estimate."

Peterborough Cathedral suffered a similar attack last November which caused an estimated �4m of damage.

Candles were placed under the plastic chairs and the building was filled with smoke, resulting in damage which is still being treated.

Firefighters at the scene said they came within 15 minutes of loosing the entire cathedral.

Mr Bentham added: "Lincoln Cathedral is one of the great medieval treasures of Europe - and among its finest and largest cathedrals.

Popular attraction

"People here are in shock and disbelief that anyone would want to destroy it.

"It's unbearable to imagine Lincolnshire without a cathedral - just horrendous."

Attracting visitors from all over the world, the building dates back to 1186.

Employing about 100 staff, it costs �50, 000 a week to run.

There will be limited access to parts of the cathedral while repair work is carried out.