It follows a case in which a man had been informed he had won almost £1 million pound.
A PSNI spokeperson: “We are all used to seeing the EuroMillions lottery paying out huge jackpots to a few lucky winners, but there are some crooks out there trying to hit their own jackpot by conning members of the public.
“An example of that was seen in Derry recently when a man received a letter to say he had won £900,000 on the ‘Euromillions International Postcode Lottery.’
“The letter had an address in Brussels and informed the recipient that he had won third place in a draw last November.”
The recipient was asked to telephone a named individual before 4 April this year or the entire fund would be returned to the “UK Board of Internal Revenue.”
The letter contained a number of grammar and factual errors and also warned that “this information must be kept away from public to avoid unwarranted abuse of the programme.”
The police spokesperson added: “This is typical of the kind of scam that will lead unsuspecting respondents to provide their banking details, or even a ‘deposit’ to secure the release of the money.”
The spokesperson concluded: “Always remember if you haven’t entered a lottery, then you can’t have won it.
“You should also remember that if it looks to good to be true then it generally is.”