President Joe Biden's administration has extended a deadline requiring investors to sell their stakes in companies "whose name closely matches, but does not exactly match, the name of a Communist Chinese military company" until May 27.

The U.S. Treasury Department's Office of Foreign Assets Control (OFAC) said in its statement, issued on Wednesday, that it had extended the Jan. 28 deadline.

Five of the companies involved are CGN Power, China National Nuclear Power, China Shipbuilding Industry, Inspur International and Sinochem International.

"In the light of the OFAC announcement, FTSE Russell will not be implementing any deletions from FTSE Russell indexes based upon 'closely matched' names at this time," FTSE Russell said, adding that it would monitor for further updates.

Former U.S. President Donald Trump's administration moved in November to prohibit U.S. investments in Chinese companies that Washington said were owned or controlled by the Chinese military in an effort to ramp up pressure on Beijing.

The blacklist now includes 44 companies including China's top chipmaker SMIC and oil giant CNOOC. The New York Stock Exchange, as well as FTSE Russell, MSCI and S&P Dow Jones, have removed as many as 15 of them from their benchmarks.

(Reporting by Marc Jones; Editing by Edmund Blair)