WASHINGTON (Reuters) -Boeing ( BA ) CEO Dave Calhoun apologized and vowed the planemaker would follow government rules after the National Transportation Safety Board said the company provided non-public information speculating about possible causes on a 737 MAX mid-air emergency, the safety panel's top official said on Wednesday.

NTSB Chair Jennifer Homendy told Reuters Calhoun called her after the NTSB criticized Boeing ( BA ) on June 27 for violating its investigation rules into the mid-air blowout of a new Alaska Airlines 737 MAX 9 door plug with four missing bolts. "He said they were revisiting with everybody what the rules are for NTSB investigations," Homendy said, calling it a "very good conversation."

Boeing ( BA ) declined further comment on Wednesday but said previously the company deeply regretted "that some of our comments, intended to make clear our responsibility in the accident and explain the actions we are taking, overstepped the NTSB's role as the source of investigative information."

The NTSB said Boeing ( BA ) would no longer see information produced during its probe. Unlike other parties, Boeing ( BA ) will now not be allowed to ask questions of other participants at a hearing on August 6-7.

The NTSB said last month a Boeing ( BA ) executive comments during a factory tour attended by dozens of journalists "released non-public investigative information and made unsubstantiated speculations about possible causes."

Homendy said Wednesday that NTSB investigators were still conducting interviews and still requesting information in the investigation and are likely to have more questions after next month's hearing. "Our investigators are getting the information they need," Homendy said.

The NTSB also said it would refer Boeing's ( BA ) recent conduct to the Justice Department.

On Sunday, the DOJ Boeing had agreed to plead guilty to a criminal fraud conspiracy charge and pay a fine of $243.6 million to resolve a U.S. Justice Department investigation into two 737 MAX fatal crashes.

Homendy told Reuters Wednesday the NTSB had "shared with the DOJ what occurred to make them aware."