SAN FRANCISCO — A California utility under fire for a deadly pipeline explosion has revealed that key information the company gave federal investigators about past problems on its ruptured gas line is being called into question by some of its employees.

Pacific Gas & Electric Co. quietly released a document in May — more than eight months after the explosion killed eight people and torched a San Francisco suburb — showing that the same transmission line had sprung a leak a few miles away more than a decade earlier.

But the company revealed this week that its own workers’ accounts challenge the accuracy of that document given to the National Transportation Safety Board.

The conflicting accounts about the 1988 leak is just the latest development in a long string of concerns about the company’s haphazard record-keeping in the wake of the September blast in San Bruno.

NTSB Chairwoman Deborah Hersman previously has chided the company for coming forward with critical information about prior failures so long after the agency began its probe, saying it could hamper investigators’ progress.