The 45-year-old woman received a letter in the post from Bono Lotto Espanyol saying she had won 646,924.5 euros ($A1.3 million).

When she contacted the company she was told to send money through a Western Union transfer to release the winnings.

She sent about $3000 before becoming suspicious and contacting police.

Police said the woman's experience should serve as a warning to all Redlanders.

"In these tough economic times, money is tight and people are taking risks they would not normally take," said Acting Senior Sergeant Dan Hodgson, Officer-in-Charge of Capalaba police.

"You've got to be extremely cautious. As soon as they start asking for money, alarm bells should be ringing."

Acting Snr Sgt Hodgson said residents should be particularly cautious of anything requiring a Western Union money transfer as this was a common way for fraudsters to receive money.