Police and the fire service are urging people to report suspicious activity around straw stacks in a bid to reduce the risk of arson attacks.

The number of deliberate stack fires increased last year to 17, up five incidents compared with 2012 to 2013.

Historically, stacks tend to be targeted between July and October.

Officers are working with Cambridgeshire Fire and Rescue Service, Cambridgeshire Countryside Watch and the National Farmers’ Union to launch Operation Armitage.

Inspector Ian Ford said: “These fires cost businesses thousands of pounds and also cause huge disruption to rural communities and motorists.

“We are using a range of tactics, including the use of covert equipment, to identify and catch anyone committing this type of crime. But we also need people to report any suspicious activity around these stacks.

“Offenders face being arrested and put before the courts. However, there is also an important safety issue to consider. Those responsible are not only risking their own lives but potentially the lives of others.”

Arson liaison officer at Cambridgeshire Fire and Rescue Service, Martin Boome, said: “We take a dim view of any kind of fire which is started deliberately - including stack fires. This type of fire has the potential to kill, not only those in the nearby vicinity, but also the arsonists themselves.

“A stack fire can tie up fire and police resources for several hours, which means people starting them deliberately are impacting on our response to other emergency calls.”

Any information regarding suspects or suspicious activities around straw stacks should be reported to police by calling 101, 999 in an emergency or Crimestoppers, anonymously, on 0800 555111.