Residents have been asked to look out for suspicious activity after a spate of arson attacks in a residential area of Carlisle.

Firefighters have been called out almost a dozen times in the past six months or so, each time to a deliberately lit fire outside the Higginson Mill flats, in the Denton Mill Lane area of Denton Holme.

In the majority of instances the flames have been confined to a bin compound beside the main building, but last week The Cumberland News reported that a portable toilet was destroyed in a blaze.

It was the fourth time this month that Carlisle firefighters had been called to a blaze at the site.

Frustrated fire crews said that the arsonists were not only potentially risking lives, but were also putting a huge strain on the physical and economic resources of the fire service.

Watch manager Bruce Wilson said he would struggle to quantify the cost, but revealed every call out requires at least one appliance and four firefighters, usually for a total of about an hour.

Mr Wilson added: “We are available primarily for serious house fires and car crashes – and when we are responding to arson fires we are less able to respond to those. Calls such as this are a waste of time and resources, as we have appliances responding to all these incidents.”

Cumbria Constabulary says it has been working with the fire service in Carlisle in relation to the fires.

PCSO Josh Jenkinson explained that every time the firefighters attend an incident at Higginson Mill, the police are also informed.

“Officers have attended to help with the investigation and attain any possible forensic evidence,” he explained.

“There have been a number of fires in the area and police are considering that these are not accidental and may have been started deliberately.”

The force says it has increased both its PCSO and police officer patrols in the area to provide reassurance to the local community and to look for any suspicious activity.

The police Community Safety Team has also been working with the letting agency for the site and talking to residents at Higginson Mills, to offer crime prevention and safety advice.

A fire service spokesman had previously revealed that the same person or people is believed to be behind all of the incidents. While the incidents have so far remained low key, on at least one occasion crews have become concerned that the bin compound – which has a timber roof – could catch alight.

Anyone who spots anything or anyone suspicious in the area, or who has any information in relation to these incidents, is urged to call Cumbria police on 101. Alternatively, call Crimestoppers anonymously on 0800 555 111.