US President Joe Biden on Monday joined Threads, Meta's social media rival to Elon Musk's X, just days after the White House blasted the tech baron for pushing anti-Semitism.

"Folks, it's President Biden," said his first post, which he made on his 81st birthday. "You're hearing from me today from a new platform but my message to you hasn't changed."

"I don't see a dark, dismal, divided future for America," Biden added. "I see an America about to take off." 

Mark Zuckerberg's Meta, the home of Facebook and Instagram, launched Threads in July in a bid to depose Musk's X, then known as Twitter, as the go-to platform for celebrities, companies, and governments to make public statements.

The White House confirmed it had launched Threads accounts for the president, First Lady Jill Biden, Vice President Kamala Harris, her husband Douglas Emhoff, and the White House itself in English and Spanish.

"Threads is an additional way we can communicate with the American people about this administration's historic actions to create 14 million jobs, lower prescription drug costs, and protect freedoms and more," a White House official said.

The official added that the launch had been in the works for several weeks.

But Biden's debut on the platform comes only three days after a White House spokesman condemned Musk, the world's richest person, for the "abhorrent promotion" of an anti-Semitic conspiracy theory.

Advertisers have also deserted X after the controversial Tesla and SpaceX tycoon last week replied to an anti-Semitic post on the platform with the words: "You have said the actual truth."

The White House repeated its condemnation of Musk on Monday but said there were no plans as yet to change US proposals to use a version of his Starship rocket for future Moon landings.

"That doesn't mean that we accept or agree with or condone, in any way, that anti-Semitic rhetoric that he pushed," National Security Council spokesman John Kirby told a briefing.

Meanwhile, White House communications director Ben LaBolt promoted the president's first Threads post — on X.