“Anyone who wishes to do remote work must be in the office for a minimum (and I mean minimum) of 40 hours per week or depart Tesla,” the memo said.

Reuters could not immediately verify the authenticity of the memo. Tesla did not respond to a request for comment. Musk could not be reached for comment.

In response to the memo that was tweeted from an unverified account, the billionaire, who has proposed to take Twitter Inc TWTR.N private in a $44 billion deal, said, “They should pretend to work somewhere else.”

Musk would “review and approve” any cases where they could not meet the minimum, according to the memo.

Tesla joins a wave of companies mandating a return to office for employees. While some big employers have embraced voluntary work-from-home policies permanently, others including Alphabet Inc’s GOOGL.O Google are betting that it is best to push in-person interactions among colleagues.

Twitter CEO Parag Agrawal tweeted in March that Twitter offices would be reopening but employees could still work from home if they wanted to.

“Wherever you feel most productive and creative is where you will work and that includes working from home full-time forever,” Agrawal said in a tweet dated March 3.

(Reporting by Tiyashi Datta in Bengaluru; Editing by Anil D’Silva)