U.S. Markets close in 1 hr 1 min

Infineon, Cree warn U.S. might stop Wolfspeed sale

* CFIUS informed Infineon that deal poses security risks

* Infineon agreed last year to buy Wolfspeed for $850 mln

* U.S. blocked takeover of Germany's Aixtron last year (Adds context, Cree statement)

FRANKFURT, Feb 8 (Reuters) - German chipmaker Infineon and U.S. LED lighting maker Cree warned that Cree's planned sale of Wolfspeed Power and RF to Infineon might not go ahead, citing security concerns by the U.S. government.

The Committee on Foreign Investment in the United States (CFIUS) informed the two companies that the deal poses a risk to U.S. national security, Infineon said on Wednesday, adding that CFIUS had so far not identified any mitigation measures.

The companies did not specify the nature of the security concerns.

"Against this background, Infineon is of the opinion that there is a considerable risk that the transaction, as agreed, is not going to close," Infineon said, adding that it was continuing to work closely with CFIUS and Cree to find a solution.

Cree, in a separate statement, said the parties were exploring alternatives to modify the transaction. It said there was no guarantee that a new deal structure could remove CFIUS concerns.

Infineon in July agreed to buy Wolfspeed Power and RF - which includes the silicon carbide substrate business for power, RF and gemstone applications - for $850 million, betting on new energy-efficient chips it expects will dominate the market in the next decade.

The news marks the latest intervention by U.S. authorities with regard to M&A transactions that involve critical technology. In December, China's Fujian Grand Chip Investment Fund dropped its takeover bid for German chip equipment maker Aixtron after the United States blocked the deal on security grounds by stopping Fujian from buying Aixtron's U.S. business.

Aixtron makes devices which produce crystalline layers based on gallium nitride that are used as semiconductors in weapons systems.

(Reporting by Christoph Steitz; Editing by Georgina Prodhan and Leslie Adler)