Elon Musk denied leading a "hostile takeover" of the US government and defended his cost-cutting plans as he made a surprise first appearance at the White House on Tuesday.

The world's richest man took questions from reporters in the Oval Office as he stood next to President Donald Trump, who has tasked him with slashing the size and spending of the federal government.

Trump then signed an order giving Musk's Department of Government Efficiency (Doge) more authority to cut the federal workforce. It instructed the heads of government agencies to comply with Doge.

The agency has been criticised by Democrats who have accused it of a lack of transparency, and its efforts have also been hampered by legal challenges.

But Musk, who was questioned by reporters for the first time since Trump took office last month, described sweeping government cuts as "common sense" measures that are "not draconian or radical".

"The people voted for major government reform and that's what the people are going to get," he said. "That's what democracy is all about."

"I fully expect to be scrutinised," he added. "It's not like I think I can get away with something."

The billionaire technology entrepreneur, who himself was appointed and not elected, described federal workers as an "unelected, fourth, unconstitutional branch of government" that he said has "more power than any elected representative".

The 53-year-old owner of Tesla, X and SpaceX wore a black Make America Great Again cap and cracked the occasional joke with reporters who asked him about his critics. He had his young son, who was introduced by Trump, on his shoulders for part of the news conference.

"It's not optional for us to reduce the federal expenses," Musk said. "It's essential. It's essential for America to remain solvent as a country."

Musk was also asked about a recent false claim that the US government was sending millions of dollars worth of condoms to Gaza. "Some of the things that I say will be incorrect and should be corrected," Musk replied.