Huntingdonshire farmers have lost ­thousands of pounds after arsonists set fire to four huge stacks of straw in just over a week.

A firefighter works to extinguish the flames after the arson attack in Papworth Everard. Picture: CAMBS FIRE AND RESCUE SERVICE.A firefighter works to extinguish the flames after the arson attack in Papworth Everard. Picture: CAMBS FIRE AND RESCUE SERVICE.

Concern among the farming ­community is mounting after fires in Brampton, Papworth Everard, Wennington and Warboys - police are remaining open-minded about whether they are linked.

The latest was on Sunday (September 7) when ­firefighters were called to a blazing stack of about 250 tonnes near woodland off Stirling Way, Papworth Everard, just before 5pm. They were there for more than seven hours, returning regularly to check it was out.

The largest so far was on Friday, September 5, when 750 tonnes of straw - worth about £20,000 - was set on fire off Grafham Road, Brampton, at 2.20am. At least 30 ­firefighters tackled the blaze and used fans to encourage it to burn quicker, stopping it spreading to farm buildings.

John Sewell, of GB Sewell and Partners, who owned the Brampton stacks, said: "There is great concern - you have sleepless nights where you just don't know what you are going to find in the morning.

A burning stack of straw in Wennington. Picture: CAMBS FIRE AND RESCUE SERVICE.A burning stack of straw in Wennington. Picture: CAMBS FIRE AND RESCUE SERVICE.

"It is a financial loss, although we are insured. At the moment we can still get insurance for stack fires but it is ­becoming more difficult."

Arsonists also targeted a 350-bale stack in Wennington at 1.15am on September 1. The other was off the A141 in Warboys at 5.30pm on August 31, when two large bales were well alight and close to another large stack. The farmer helped firefighters by using a digger to spread and put out the straw.

The National Farmers' Union (NFU) advises farmers to remove hay and straw from fields as soon as possible after harvesting, store it separately from ­buildings and access routes, to record the temperature regularly and to increase security.

Brian Finnerty, regional ­communications adviser for the NFU East Anglia, said: "These are incidents that tie up a lot of fire resources - it costs £400 an hour for a fire engine to attend."

Martin Boome, arson liaison officer at Cambridgeshire Fire and Rescue Service, said: "When we had a spike in 2005 [of stack fires], we probably had about 10 in the same amount of time.

"The season is going to be coming to an end pretty shortly - all the straw has been baled and it is there in stacks.

"It is a concern for me as the arson liasion officer and we will be attempting to find the culprits."

He said there were plans in place, including hidden cameras, signs and using forensics when incidents occur.

He said: "They are putting firefighters' lives at risk as well as members of the community.

"They don't know what's going to happen when the fire spreads."