SpaceX has fired several employees who were critical of founder and CEO Elon Musk, the aerospace firm confirmed in an internal message to employees on Thursday.

According to news agency AFP, which confirmed the authenticity and contents of the internal communication, SpaceX Chief Operating Officer (COO) Gwynne Shotwell announced that a “small group” of employees had penned a letter critical of Musk and had sought their colleagues’ support for the same.

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Shotwell, however, said that some workers felt “uncomfortable, intimidated and bullied, and/or angry because the letter pressured them to sign onto something that did not reflect their views.”

“We have too much critical work to accomplish and no need for this kind of overreaching activism,” Shotwell further said, adding that the aerospace company had “terminated a number of employees involved.” She did not specify how many employees had been fired.

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The letter in question penned by the now-terminated employees, first reported by The Verge, was critical of Musk and his behaviour on microblogging website Twitter and the recent sexual harassment allegations against him, and described the 50-year-old billionaire “a frequent source of distraction and embarrassment for us.”

“As our CEO and most prominent spokesperson, Elon is seen as the face of SpaceX — every Tweet that Elon sends is a de facto public statement by the company,” the letter had further said.

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SpaceX’s move to sack employees critical of Musk may also, intentionally or unintentionally, signal to Twitter employees that criticism of the ‘free speech absolutist‘ billionaire will not be tolerated once he completes his $44 billion acquisition of the microblogging company.

Musk, who delivered his first address to Twitter employees on Thursday, was harshly criticised in internal chats among employees, criticism to which the 50-year-old has responded with a one-worded reply, “Interesting.”