Elon Musk says some Tesla drivers were removed from beta tests for its Full Self-Driving software for not paying attention to the road

• Tesla CEO Elon Musk said his company pulled access for some Full Self-Driving software testers.
• Tesla "revoked beta where drivers did not pay sufficient attention to the road," Musk said.
• On Friday, CNBC reported NTSB chair Robert Sumwalt sought new requirements for public testing.

Tesla CEO Elon Musk on Friday said the carmaker had expanded the public testing pool for its Full Self-Driving software to about 2,000 vehicle owners but also revoked access for drivers who didn't pay close attention to the road.

Tesla "revoked beta where drivers did not pay sufficient attention to the road," Musk said on Twitter late Friday. "No accidents to date."

Musk didn't offer further details about how many drivers have lost access, or how Tesla made decisions about pulling access. Insider has reached out to the company for comment.

Musk's statement followed a Friday report saying the National Transportation Safety Board chairman called for increased scrutiny of self-driving software.

On Friday, CNBC reported that NTSB Chairman Robert Sumwalt had in February sent a letter to the National Highway Traffic Safety Administration asking for updated requirements for carmakers testing software like Tesla's on public roads.

Sumwalt's letter mentioned Tesla by name 16 times, as CNBC reported. He wrote that Tesla was testing its software on public roads "with limited oversight or reporting requirements."

He added: "Although Tesla includes a disclaimer that 'currently enabled features require active driver supervision and do not make the vehicle autonomous,' NHTSA's hands-off approach to oversight of [automated vehicle] testing poses a potential risk to motorists and other road users."

A week ago, Musk said Tesla would double the size of its public beta testing program for version 8.2 of its software. "Still be careful, but it's getting mature," he said.

He added that he expected the beta testing program to expand tenfold for software version 8.3, which would be released in "probably two or three weeks." On Friday, he said the next "significant release will be in April."

A cache of emails between Tesla and California regulators were made public by a transparency advocacy group, PlainSite, on Friday.

In the emails, a Tesla lawyer said the company had "made it abundantly clear" to beta testers that the system "does not make the vehicle autonomous and that the driver is responsible for being fully attentive at all times."