Police are treating a fire that sent thick plumes of black smoke hundreds of feet into the north-east sky as suspicious.
Officers have launched a probe into the blaze, which caused thousands of pounds worth of damage at Peterhead Harbour on Thursday night.
Officers and firefighters were sent the industrial unit in the Greenhill Road area of the town after several polystyrene blocks caught fire.
The dark smoke could be seen from as far as Ellon – 15 miles away – as firefighters tried to dampen the flames.
The area around the fire was closed and access to the harbour was temporarily restricted.
Last night, Police Scotland launched an appeal for information and asked for anyone who was in the busy area at the time to contact the force if they saw anything.
PC Craig Beedie, of the Buchan Community Policing Team, said: “This incident took place during the early evening when the area would have been busy and I urge anyone who noticed any suspicious activity in the area or who has any knowledge to come forward.”
Local councillor Alan Buchan urged local people to cooperate.
He said the harbour was a dangerous place for a fire to break out.
“People should be vigilant about anything strange going on around the harbour, because once a fire takes a hold you don’t know where it could spread to,” he said.
“There’s so many fishing boats and tanks of fuel beside the quay, it could easily cause a chain reaction which could get a whole lot worse.”
Earlier this year, residents had seen youngsters running from the scene of a suspicious fire in the port’s St Peter Street with “blackened faces”.
It is believed the children had been playing in an abandoned shed before setting it on fire.
Firefighters had to dampen the scene because of the presence of cancer-causing asbestos.
No one was injured in either incident.
Trevor Ashwell, the fire service’s watch manager in Peterhead, urged people to cooperate with wilful fire-raising investigations.
“What we don’t want is accidents to happen and people to get injured – whether that’s the perpetrators lighting the fires or innocent bystanders or properties,” he added.
Anyone with information can contact police on 101 or Crimestoppers on 0800 555 111 if they wish to remain anonymous.