London, Dec 17 (IANS): Use caution before participating in any gift exchange programme on Facebook as a Christmas con is doing the rounds on social media to take advantage of your generosity during the festive season, warns a report.

Christmas is meant to be the time of giving, but con artists are capitalising on that in a cynical scam on Facebook, Express.co.uk reported on Saturday.

The online "Secret Sister Gift Exchange" scheme claims that participants will receive up to 36 gifts in exchange for sending one gift valued at $10.

The Better Business Bureau (BBB) in America, a non-profit focused on advancing marketplace trust, earlier warned that the exchange has been circulating on social media sites and advised consumers to completely ignore it altogether.

How does this scheme work?

It claims that if a consumer purchases one gift for a stranger, he/she will receive as many as 36 gifts in return, a typical pyramid scheme.

And starting this gift exchange comes with a catch -- you need to disclose your personal information, such as your home address.

This is on Facebook instead of the old way of using letters because social media allows it to spread a lot faster, the BBB said in its advisory.

"To avoid this scam, the best thing to do is completely ignore it altogether. Do not give out personal information to anyone," it said.