WASHINGTON, June 12 (Reuters) - The U.S. Treasury Department on Wednesday announced new sanctions on over 300 entities and individuals aimed at cutting off Russia's access to products and services needed to sustain military production for its war in Ukraine, including dozens of Chinese suppliers.

U.S. officials have expressed increasing concern over Russia's ability to procure advanced semiconductors, optical equipment and other goods needed to produce advanced weapons systems despite prior sanctions.

The sanctions target third party firms and entities, including dozens of suppliers of electronics in China. The action stops short of imposing secondary sanctions on banks in China and other countries where Treasury has warned that dealings with Russian entities could cut institutions off from dollar access.

But the Treasury did say it was modifying the sanctions on previously targeted Russian banks, including VTB and Sberbank, to include branches and subsidiaries in China, India, Hong Kong, Kyrgyzstan and other locations. (Reporting by David Lawder; editing by Rami Ayyub)