Scores of reported fuel thefts from HGVs has prompted Suffolk police to urge hauliers to protect their assets.
The force said that between 1 August and 18 November there were 30 incidents reported to police where lorries had large volumes of diesel syphoned from their tanks.
The majority of the thefts took place while HGVs were parked overnight in laybys on the A14 and A12.
The police said it was aware that not all incidents are reported and so the number of thefts is likely to be higher.
The warning came after two arrests were made in relation to the theft of fuel from lorries.
Officers from Suffolk constabulary stopped a vehicle on the A14 near Newmarket which was suspected to be involved in the theft of fuel. The occupants, two men in their 30s, were both arrested on suspicion of theft and of going equipped to steal.
The pair were subsequently bailed to return to police on 20 February next year.
Detective Inspector Stuart Dolan said: “With the increase in the price of fuel in the past year we have seen a rise in the number of these types of thefts.
“Thieves are damaging and breaking fuel caps in a bid to get to the fuel. I would urge any lorry drivers and haulage company owners to take steps to prevent themselves from becoming victims.
“We have also seen the theft of fuel elsewhere, such as from farm storage tanks.”