Musk mocked the staffers in response to a tweet from options flow platform Unusual Whales, which cited reporting from tech news site Protocol: "Elon has fired numerous employees who were critical of him on Twitter and the company's Slack, according to Protocal."

"I would like to apologize for firing these geniuses. Their immense talent will no doubt be of great use elsewhere," Musk replied.

On Monday, Musk axed a Twitter engineer who publicly accused Musk of making a false claim about the platform. Since then, a number of Twitter staffers have criticized Musk either on Twitter or in internal Slack channels.

Those employees, according to tech writer Casey Newton and others, have been swiftly fired.

"We regret to inform you that your employment is terminated immediately," an email to said employees reported by Newton said. "Your recent behavior has violated company policy."

Newton said that while the number of such employees who've been fired is uncertain it "seems like it's more than 10 people," though he later posted that employees "say it appears that around 20 people have been fired so far for their Slack posts."