WASHINGTON (Reuters) -Billionaire Elon Musk, who has been ramping up criticism of U.S. President Joe Biden, has donated to a political group working to elect rival presidential candidate Donald Trump, Bloomberg reported on Friday, citing sources.

The report did not indicate how much Musk donated but added it was "a sizable amount" given to a group called America PAC.

Bloomberg reported that the PAC - a group that can receive unlimited contributions for political activity - is next required to disclose its list of donors on July 15.

In March, Trump, a former U.S. President who is expected to be formally nominated next week as the Republican Party's candidate for the Nov. 5 election, met with Musk and other wealthy donors.

In response to reports of the meeting, South Africa-born Musk posted on X: "Just to be super clear, I am not donating money to either candidate for US President." In May, he also denied media reports that there had been talks over a potential advisory role for him in any Trump presidency.

Musk, the world's richest person who runs electric car maker Tesla, rocket maker SpaceX, social media company X and other companies, did not respond to Reuters' request for comments.

Musk in recent years has more fully embraced the Republican Party, which has weighed on the reputation and sales of Tesla, the biggest source of his wealth.

Trump last month reiterated his pledge to immediately abandon the Biden administration's "mandate" to support the electric vehicle industry. But he added: "I'm a big fan of electric cars. I'm a fan of Elon."

"He does an incredible job with Tesla."

Musk said they had "some conversations" and Trump is a "huge fan of the Cybertrucks," referring to Tesla's electric pickup trucks.

While he has publicly criticized Biden's policies on immigration and electric vehicles and even his age, Musk has not made any formal endorsement in November's contest and Trump has said he did not know if he has Musk's support.

He has also endorsed antisemitic comments on X, though Musk has denied being antisemitic.

Musk's views have hurt his standing among some consumers, according to a CivicScience survey shown exclusively to Reuters.