A safety system designed to help subway trains avoid crashes had malfunctioned months before a deadly Washington Metro crash in June, newly obtained records show.

A crash was avoided March 2 only after the subway train's operator used an emergency brake to avoid hitting another train, according to records obtained by the Washington Post. A review of computer logs later determined there had been a problem with the Automatic Train Protection system, according to the account published Sunday.

National Transportation Safety Board spokeswoman Bridget Serchak told the newspaper that investigators probing the June 22 crash had learned of the March incident from a committee that monitors Metro — a point disputed by Metro in a statement issued later Sunday.

The transit agency said NTSB investigators were told about the March incident the day after the June crash, which killed nine and injured more than 70 when a train slammed into another train stopped on the tracks.

• Click here for photos of the crash.

Metro's chief safety officer, Alexa Dupigny-Samuels, added in Sunday's statement that "the two incidents are not related."

"On March 2 the problem was identified as a failed component on board a train, and that component has been replaced," the statement said. "In the case of the June 22 collision, the National Transportation Safety Board is looking at the track circuit as having played a role in the accident, however the NTSB has yet to identify the root cause of the accident."

The safety system has been a subject of concern for the Tri-State Oversight Committee, formed as part of an effort to improve oversight of the nation's subway systems, The Washington Post reported, citing minutes from committee meetings.

The minutes from an April meeting said Metro was trying to recreate the March failure but had been unable to do so; minutes from a May meeting said Metro's "assessment of this hazard is ongoing;" and minutes from a July 8 meeting indicate the panel still had not received a response to an April 29 letter to Metro. The panel also discussed a June 3 letter in which a Metro worker alleged "that the ATP system was unreliable."

Metro said in its statement that its own attempts to recreate the March incident led to the discovery of the failed relay, findings it said were verified by outside experts.