The reports, first published by The New York Times, fanned concerns about the SpaceX and Tesla chief's influence in the White House as an unelected tycoon who has become Trump's closest advisor.

Democrats have blasted Trump for handing administration policy to Musk, the president's cost-cutter-in-chief, despite him undergoing no background checks and heading companies with government contracts worth billions.

According to the Times, Musk was set to receive a briefing Friday on US military plans in case of a war with China, including maritime tactics and targeting plans.

The Wall Street Journal and the Washington Post also reported on the briefing.

Tensions have soared between Washington and Beijing as the world's two largest economies impose a slew of tariffs on each other's imports.

Defense Secretary Pete Hegseth confirmed that Musk would visit the Pentagon on Friday but said the "informal meeting" would focus on innovation and efficiencies, not "top secret China war plans".

Trump also refuted claims that China would be on the agenda.

"China will not even be mentioned or discussed," he posted on his TruthSocial platform, branding the story "completely untrue."

Musk joined the chorus of criticism of the Times, which Trump has often accused of spreading "fake news."

"The New York Times is pure propaganda," Musk posted on his social media platform X.

Musk, in a separate post replying to Hegseth, said Friday's meeting would not be his first visit to the US Defense Department.

"I've been to the Pentagon many times over many years. Not my first time in the building," he wrote.