THESSALONIKI, Greece (AP) — A father and son duo in Greece were arrested for selling adulterated sunflower oil marketed as olive oil, police said Saturday.

A raid in a warehouse outside the northern city of Thessaloniki on Friday yielded over 13 tons of the oil, with slightly more than half already packaged in tin cans and plastic bottles and the rest in a tank, police said.

The pair, aged 80 and 36, bought the sunflower oil in Bulgaria, not far from Thessaloniki, and added coloring agents to pass it off as extra virgin olive oil. Some of it they sold in Bulgaria and the rest in Greece, police said.

The pair were provisionally released after interrogation by a magistrate. Oil samples have been sent to a laboratory to determine whether the coloring agents are dangerous.

Hot weather over the summer hit olive oil production especially hard, sending prices skyrocketing. A 5-liter (1.3-gallon) can of oil is sold retail at 57 euros ($62) from 26 ($28.30) last year.

Besides cases of adulteration, gangs have been breaking into warehouses to steal oil and olives. There have even been break-ins into olive groves, with thieves chopping off tree branches.