(Reuters) - President Donald Trump's billionaire ally Elon Musk on Tuesday directed his ire at U.S. law firms that have teamed up with advocacy groups to challenge the Republican's sweeping policy changes in court.

"Which law firms are pushing these anti-democratic cases to impede the will of the people?" Musk, the world's richest man, wrote on his social media platform X.

The post was his first to target law firms involved in cases against the Trump administration, though he did not identify a specific firm. Musk did not immediately respond to a request for comment.

The Tesla CEO and owner of X, who has been spearheading efforts to slash the federal workforce and spending, also criticized judges who have issued rulings that paused Trump's executive actions. "Democracy in America is being destroyed by judicial coup," Musk wrote in a separate post on X.

The post on law firms focused on a ruling by U.S. District Judge Angel Kelley that temporarily blocked the administration's sharp cuts to federal grant funding for universities, medical centers and other research institutions.

That lawsuit was brought in Boston by Democratic attorneys general from 22 U.S. states challenging cuts adopted by the National Institutes of Health. Two other related lawsuits related to NIH funding have been brought by groups represented by law firms Jenner & Block and Ropes & Gray.

The two law firms, which did not immediately respond to requests for comment, are among more than eight large and medium sized U.S. law firms that have signed on to lawsuits against the Trump administration related to funding cuts, immigration restrictions and transgender rights.

Many of the firms, including Gibson, Dunn & Crutcher, Hogan Lovells, Jenner & Block and Perkins Coie, are handling the cases without charge. The firms either declined to comment or did not immediately respond to requests for comment on Musk's post about law firms.

Musk has used his social media megaphone in the past to criticize prominent law firms by name.

In 2022 he denounced Perkins Coie, writing on X, then known as Twitter, that they "thrive on corruption" in reference to the firm's past work for Trump's 2016 Democratic election opponent Hillary Clinton.

Most of the more than 50 lawsuits opposing Trump policy moves so far have not been brought by law firms, but rather by legal advocacy groups, unions, Democratic states and federal grant recipients.