HGVs parked along the A14 are being targeted by thieves for fuel with vehicles being damaged in the process, police have warned.
Suffolk constabulary urged drivers and operators to take security measures and said there had been half a dozen incidents in the last few weeks alone in laybys and lorry parks.
These included three thefts in one night this month, at Creeting St Peter, Creeting St Mary and Herringswell Road in Kentford.
Other places where diesel has been stolen from lorries included Trimley St Martin and Haughley.
The police added that they were aware not all incidents are reported and they expected the number of thefts to be higher.
Superintendent Matthew Carney said: “We have seen a number of these types of thefts this year, particularly in the spring and now in the past few weeks.
“Thieves are damaging and breaking fuel caps in a bid to get to the fuel and I would urge any lorry drivers and haulage company owners to take steps to prevent themselves from becoming victims.
“If you are a victim, please report the incident as soon as possible.
“Equally, if you witness any suspicious activity, for example people tampering with lorries late at night, please report this straight away via 999 as this gives us the best chance to catch those responsible.”
Suffolk police said locking fuel caps and anti-siphon deterrents can make fuel less vulnerable, but these could be damaged if an offender gains access to a vehicle and fitting these devices may affect the warranty.
It said drivers noticing people loitering near vehicles should note down the time, date and location, as well as their descriptions.
It also urged hauliers to ensure their drivers adopt defensive parking measures and park in highly visible, well-lit areas or use off-road parking areas such as secure compounds or lorry parks.
The police added that fuel tanks should be as inaccessible as possible, by parking the vehicle tank close to a wall or park vehicles tank to tank.