WASHINGTON, March 20 (Reuters) - Billionaire Elon Musk, U.S. President Donald Trump's close ally, is due to be briefed on Friday by the Pentagon on the U.S. military's plan for any war that might break out with China, the New York Times reported on Thursday, citing U.S. officials.

Access to the closely guarded military plan would mark an sharp expansion of Musk's role as a Trump adviser who has spearheaded efforts to cut U.S. government spending.

It would also fuel questions about conflicts of interest for Musk, who as the head of both Tesla and SpaceX has business interests in China and with the Pentagon.

The White House has previously said Musk will recuse himself if any conflicts of interest arise between his business dealings and his role in cutting federal government spending.

The briefing for the China war plan has about 20 to 30 slides that lay out how the United States would fight such a conflict, the New York Times reported.

The Pentagon confirmed that Musk will be visiting on Friday but did not share further details. "The Defense Department is excited to welcome Elon Musk to the Pentagon on Friday. He was invited by Secretary (Pete) Hegseth and is just visiting," a Pentagon spokesperson said.

Washington and Beijing have had tense relations for years over differences ranging from access to technology, trade tariffs and cybersecurity to TikTok, Taiwan, Hong Kong, human rights and the origins of COVID-19. (Reporting by Kanishka Singh and Phil Stewart in Washington; Editing by Edwina Gibbs)