A US judge has ordered Elon Musk to give evidence for a third time as part of the Securities and Exchange Commission’s investigation into his purchase of Twitter, now called X, in 2022.

Magistrate judge Laurel Beeler issued an order giving Musk, his team and the SEC a week to agree on a date and location for the Tesla and SpaceX CEO’s testimony on Saturday.

In a court hearing in December, Judge Beeler said she would issue an order if the two sides couldn’t agree on when and where Musk would give evidence.

Beeler wrote in the order in federal court in Northern California: “The parties, at least initially, agreed to a date but ultimately the respondent did not appear and resists the subpoena on the grounds that the SEC’s investigation is baseless and harassing and seeks irrelevant information.”

“Also, he contends that the subpoena – issued by an SEC staff member appointed by the SEC’s director of enforcement – exceeds the SEC’s authority because it was not issued by an officer appointed by the president, a court, or the head of a department”, as required by the US constitution, she added.

However, Beeler said the court is enforcing the SEC’s subpoena and that the testimony is “not unduly burdensome” for Musk.

The SEC had given Musk the option to give evidence in Texas, where he lives.

The SEC has been conducting a fact-finding investigation into the period before Musk’s Twitter takeover, when the San Francisco-based social media company was still publicly traded.

The agency said it had not concluded any federal securities laws had been violated.

Musk has already given evidence in the case twice.

But since then, according to the judge’s order, the SEC has received “thousands of new documents” from various parties, including hundreds of documents from Musk.

He closed his $US44 billion ($A67 billion) agreement to buy Twitter and take it private in October 2022, after a month-long legal battle with the social media company’s previous leadership.

After signing a deal to acquire Twitter in April 2022, Musk tried to back out of it, leading the company to sue him to force him to go through with the acquisition.

The SEC and a lawyer for Musk were contacted for comment.