An investigation has been launched after around 1,800 litres of diesel was stolen from two sites in Sutherland.
Police have urged people who store fuel on their premises to be on their guard and to consider their security arrangements after the thefts.
The fuel was stolen from a construction site and a nearby farm n the Ardgay area.
The theft is believed to have happened sometime between late on the evening of Friday, July 22 into the early hours of the following morning.
The two sites are close to each other and officers believe the only way the thieves could have stolen the large quantity of fuel was by using a vehicle capable of carrying large loads.
They have also appealed for anyone who has been offered diesel for sale to contact them.
A spokeswoman for the police said: “They are particularly keen to hear from anyone who may have seen anything suspicious around the area at that time, particularly vehicles capable of carrying fuel loads.
“Officers are also appealing for anyone with knowledge of fuel being stored or offered for sale in the north area other than through recognised distributors.”
She added: “At the same time they would like to remind those who store fuel for agricultural purposes or business works to be aware that crimes of this nature are occasionally committed and police would recommend that they review their security arrangements, considering additional lighting/fencing and secure locks for access gates.
“If anyone has any information regardless, how insignificant it may appear, they are urged to contact Police on 101 or Crimestoppers on 0800 555 111.”