UPDATE 2-US FDA warns Baxter on surgical sealant promotion

* FDA says Baxter overstated effectiveness

* Company says marketing materials no longer in use (Adds company comment)

WASHINGTON May 5 (Reuters) - U.S. regulators have warned Baxter International Inc (BAX.N) that promotions for the company's Tisseel surgical sealant were misleading, a letter released on Tuesday said.

A brochure and other sales materials overstated Tisseel's effectiveness and made unsubstantiated claims that it was superior to other products, the Food and Drug Administration said in an April 14 letter to Baxter.

The FDA asked the company to immediately stop using the misleading promotions and submit a plan to disseminate messages to correct false statements.

Baxter has withdrawn the marketing materials from its sales staff and "is working with the FDA on their concerns," company spokesman Chris Bona said.

Tisseel is a spray used to stop bleeding during surgery. The FDA letter "does not concern safety and efficacy" of the product, Bona said.

The FDA posted the letter on the agency's website here. (Reporting by Lisa Richwine; Editing by Gerald E. McCormick and Tim Dobbyn)