Facebook is relying on some good, old-fashioned incentives to boost sales of Facebook Credits in Europe.

The social network announced on its developer blog that any European developer that drives more than $100,000 in Facebook Credits sales in Europe will receive an additional three percent on those sales.

Facebook said the incentive program covers sales of Facebook Credits in Europe from January 1 to March 31, and payments will be made to developers in late April.

The company added that it will evaluate the program at its conclusion and may or may not renew it.

Meanwhile, 15 million people used Credits during 2011, according to our sibling blog Inside Facebook.