The use of counterfeit coupons for groceries and other items has risen as budget-conscious consumers increasingly get their coupons from online sources.

Only about one-tenth of 1% of the 3.3 billion coupons redeemed in 2009 were fakes, according to NCH Marketing Services Inc., a coupon clearing house. But the number of fraudulent redemptions increased by 14% from 2008.

On top of that, the Coupon Information Corp., a non-profit organization monitoring fraud on behalf of food companies, has indentified 198 faulty coupons since late December -- more than the previous decade combined.

"Hard times kind of bring out the worst in some people. In this bad economy, there's more incentive to put one over on the retailers and the brands," said Matthew Tilley, director of marketing for Inmar Inc., a big coupon processor.

Food manufacturers distribute coupons via newspapers, direct-mail booklets and Web sites. After shoppers use them to buy products, the coupons are sent to clearing houses like NCH or Inmar, which verify the redemptions. Manufacturers then reimburse retailers the full value of the coupons.