The National Transportation Safety Board (NTSB) announced Thursday that it is dropping Tesla as a party in the agency's investigation into the fatal car crash in Mountain View last month, accusing the company of releasing "incomplete" information that speculated on the cause of the crash.

San Mateo resident Walter Huang suffered major injuries and later died at the hospital after his Tesla Model X crashed into a cement divider on southbound Highway 101 on March 23. Tesla officials later stated that Huang had the vehicle's Autopilot system on at the time of the crash, and claimed that he had failed to respond to multiple warnings to take the wheel and avert the crash.

Four days after the accident, the NTSB announced it was opening an investigation into the crash, and invited Palo Alto-based Tesla to cooperate through a formal agreement with the agency. But in an announcement Thursday, NTSB officials said that Tesla was removed from the investigation after violating the agreement by releasing "incomplete information" in statements to the public that had neither been vetted nor confirmed by NTSB, leading to speculation and incorrect assumptions about the cause of the crash and doing a "disservice" to the investigative process and the public.

"It is unfortunate that Tesla, by its actions, did not abide by the party agreement," NTSB Chairman Robert Sumwalt said in the statement. "While we understand the demand for information that parties face during an NTSB investigation, uncoordinated releases of incomplete information do not further transportation safety or serve the public interest."

In a letter addressed to Tesla CEO Elon Musk, Sumwalt wrote that Musk was briefed in a phone conversation on April 6 about the NTSB party system, and that Tesla officials had agreed to refrain from releasing investigative information related to the crash.

The letter goes on to say that on Wednesday, April 11, Tesla ran afoul of the agreement by issuing a statement -- without consulting NTSB or giving the agency a heads-up -- with information that the agency found "incomplete, analytical in nature, and speculated as to the cause of the March 23, 2018 crash.

"Only appropriate NTSB personnel are authorized to publicly disclose investigative findings; even then, the release will be limited to verified factual information identified during the course of the investigation," Sumwalt wrote.

Since the fatal crash in March, Tesla officials have actively updated the public on what the company has uncovered about the accident. On March 27, the company released a blog post with an early analysis of the crash site, the damage to the vehicle and the subsequent battery fire. Another blog post came out three days later claiming that vehicle logs from Huang's Model X showed he had enabled the vehicle's Autopilot function before the crash and did not put his hands back on the steering wheel in the seconds before the crash despite "several visual and one audible hands-on warning." NTSB officials indicated they were unhappy with the release of that information shortly after the blog was posted.

The April 11 statement by Tesla, released to media outlets including ABC7 News, came in response to plans by Huang's family to file a wrongful death lawsuit against the automaker. The statement strongly suggests that Huang was at fault for the crash, and that he was "not paying attention to the road" and had plenty of warnings and several hundred feet of visibility before hitting the barrier.

The statement goes on to say that there is a "false impression" that the Autopilot system designed by the company is unsafe, despite data showing the contrary, and that it results in fewer crashes on the road.

Following NTSB's announcement Thursday, Tesla released a statement to media outlets including the San Francisco Chronicle saying that the company had decided Tuesday to withdraw from the party agreement. Tesla again emphasized the safety of its cars and said the company would be making an official complaint to Congress over its dealings with NTSB.

"It's been clear in our conversations with the NTSB that they're more concerned with press headlines than actually promoting safety," according to the statement issued to media outlets Thursday. "Among other things, they repeatedly released partial bits of incomplete information to the media in violation of their own rules, at the same time that they were trying to prevent us from telling all the facts."

An NTSB spokesman declined to comment on Tesla's allegations Friday morning, telling the Voice that the press release Thursday is an accurate recount of events this week.

Revoking the party status of companies in NTSB investigations is rare, but not unheard of. The agency's press release notes that the safety board dropped the National Air Traffic Controllers Association in 2009 during an investigation into a midair collision over the Hudson River, and in 2014 revoked the party status of United Parcel Service (UPS) and the Independent Pilots Association over a flight crash investigation in Birmingham, Alabama.

Participation in the NTSB's party system "allows the sharing of investigative information with all parties that agree to the terms of the party agreement during the early fact-gathering phase of an investigation," NTSB officials stated Thursday.

"This sharing ensures that a party to an investigation has sufficient information to take any immediate actions necessary to ensure safety," the agency said.

Although NTSB investigations are thorough and take between one and two years to complete, safety board officials said the the process is transparent and includes the public release of reports and information, and does not hinder quick action to improve transportation safety.

"There is nothing in the party agreement that prevents a company from enacting swift and effective measures to counter a threat to public safety," Sumwalt said in the statement.

The action by the NTSB does not revoke Tesla's party status in other ongoing investigations into crashes in California, including a Tesla Model X crash in Lake Forest last year, as well as a Jan. 22 Tesla Model S crash in Culver City. NTSB also noted that it expects Tesla's future cooperation with data requests related to the Mountain View investigation.