The new campaign, which is being publicised on police social media accounts, asks people to inform officers if they spot a pizza on sale for under six euros (£4.50), national broadcaster Yle reports . "Unless a pizza is on temporary sale there is no way a legitimate establishment can offer pizza for less than six euros," Det Insp Minna Immonen of the Uusimaa police department is quoted as saying. Police are trying to crack down on the "grey economy", which costs the country millions of euros in lost tax revenue each year. They also want people to make sure they get a receipt for their pizzas, regardless of value.