Elon Musk has several different businesses, from making electric cars at Tesla to building rocket ships at SpaceX. But one of his lesser-known businesses has been in the spotlight lately over accusations that it needlessly killed about 1,500 animals. 

Neuralink, Musk’s brain technology startup, has come under fire recently for its animal testing practices, and the company is being investigated for violations of animal welfare. Over 20 current and former employees claim that the tests were being conducted hastily, and that workers were under pressure from Musk to expedite trials, leading to botched experiments and excessive animal deaths.   

Now, a major medical ethics advocacy group, the Physicians Committee for Responsible Medicine, has requested the Food and Drug Administration hold Neuralink accountable for violating protocols on biological tests, and disqualify the data obtained from animal testing, the Washington Post reported Tuesday. It has also asked the FDA to ban additional animal tests by Neuralink.

“Between what we’ve seen in public records and what has been reported, it’s hard to imagine that Neuralink’s animal experiments meet FDA’s requirements,” Deborah Dubow Press, associate general counsel with the Physicians Committee, said in a statement.

In an interview with Fortune, Ryan Merkley, director of research advocacy for the organization, said that it was concerned that the documents Neuralink was providing to the FDA were not “trustworthy.”

“We want FDA to take a very close look at whatever Neuralink is providing, and ideally, we want the FDA to proactively launch an investigation because it’s clear that over the years from public records and whistleblower reports that Neuralink has not followed its own internal protocols.”

Neuralink did not reply to Fortune’s request for comment.

If the FDA does dismiss the results collected thus far, it could threaten Neuralink’s business plans for its brain implants and the company’s stated vision of creating a “brain-computer interface.” At a Neuralink event in November, Musk said that implants on human brains were roughly six months away and that the company had already submitted its request to the FDA. He presented a video of a monkey named Pager playing “monkey mind pong,” which resembles ping-pong but he plays it in his mind. Musk claimed that Pager would not be able to do so without using a brain implant, which he described as “replacing a piece of the skull with a smartwatch.”

“Before we would even think of putting a device in an animal, we do everything we possibly can with rigorous benchtop testing, so we are not cavalier,” Musk said during the presentation. He also said that whenever a device was implanted into a sheep, pig, or monkey, it was done to confirm their testing results rather than to explore the outcomes of the experiment on the animal.

The Physicians Committee for Responsible Medicine based its request to the FDA on 700 pages’ worth of documents that were obtained after suing the California National Primate Research Center at the University of California–Davis, which was tasked with conducting the Neuralink animal experiments. The tests were conducted on rhesus macaques, a pink-faced species of monkey originating in Asia, the Washington Post reported.