US market regulators on Thursday asked a judge to order Elon Musk to comply with a subpoena to answer questions about his purchases of Twitter shares last year.

Musk, who beefed up his stake in Twitter before buying the company for $44 billion, did not show up for a scheduled deposition in September with the Securities and Exchange Commission (SEC), according to a legal filing.

"Musk's ongoing refusal to comply with the SEC's administrative subpoena is hindering and delaying the SEC staff's investigation to determine whether violations of the federal securities laws have occurred," the commission said in court documents.

"Accordingly, the SEC now asks the court to compel Musk to appear for investigative testimony."

The SEC investigation pertains to all of Musk's purchases of Twitter stock in 2022 as well as his statements and filings with market regulators, court documents stated.

Musk took part in two half-day depositions in July with the SEC, which told the court it has since received "thousands of documents" that have raised questions they want the billionaire boss to answer.

Musk objections to the latest deposition included an accusation that the SEC is using its power to "harass" him, the commission said in the filing.

"The SEC has already taken Mr. Musk's testimony multiple times in this misguided investigation - enough is enough," Musk attorney Alex Spiro said in reply to an AFP inquiry.

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