Stephen K. Bannon, President Trump’s former White House chief strategist, has renewed his feud with Elon Musk, the richest man in the world and a top Trump adviser, calling him a “parasitic illegal immigrant” in an interview published online on Tuesday.

Mr. Bannon made the comments in an interview with UnHerd, a British news site, that took place last week.

“Musk is a parasitic illegal immigrant. He wants to impose his freak experiments and play-act as God without any respect for the country’s history, values or traditions,” Mr. Bannon told the interviewer. He appeared to be referring to news reports that Mr. Musk, who was born in South Africa and who has become an aggressive voice against undocumented immigrants, overstayed his visa as he built a company in the United States. Mr. Musk has denied the accusation.

Mr. Bannon has repeatedly criticized Mr. Musk, calling him a “truly evil person” before the inauguration last month and vowing to prevent him from having full access to the White House. But Mr. Musk, who initially irritated Mr. Trump with his omnipresence at Mr. Trump’s private club, Mar-a-Lago, during the presidential transition, has made himself invaluable to Mr. Trump as an internal enforcer of executive orders and efforts to aggressively cut spending and reduce the size of the federal work force.

That has made Mr. Musk a significant focus of anger from Democratic elected officials, alongside the president who empowered him.

“It’s pretty evident the president’s using him as an armor-piercing shell that’s delivering blunt force trauma against the administrative state,” Mr. Bannon said in the interview. But he also described Mr. Musk’s work as “performative” and complained that Mr. Musk had not focused on the Pentagon, with which Mr. Musk’s private companies have many contracts. (Mr. Trump has suggested Mr. Musk will at some point look at Pentagon spending.)

Despite his dramatic and fractious departure from the White House in 2017, Mr. Bannon became close with Mr. Trump again in the final year of Mr. Trump’s first term. Mr. Bannon is still a close ally and, more significantly, a popular figure within the Trump movement: His show, War Room, is watched closely by a number of Trump allies, as well as the president himself.

While Mr. Bannon has endorsed some of the efforts that Mr. Musk’s so-called Department of Government Efficiency group is taking, he has condemned Mr. Musk as not pure to the movement that propelled Mr. Trump back into office.

Mr. Musk has generally avoided responding to the jabs Mr. Bannon has made over the last few months. Two weeks ago, he posted on X, his social media website, an insult he’s used about a number of people in private discussions since joining Mr. Trump’s team.

“Bannon is a great talker, but not a great doer,” Mr. Musk wrote. “What did he get done this week? Nothing.”

Neither a White House representative nor Mr. Bannon immediately responded to a message about the interview.