(Updates with Pemex statement)
MEXICO CITY, Jan 12 (Reuters) - An accident at the Ciudad Madero refinery of Mexican state-owned oil firm Pemex killed one worker on Thursday, but the incident will not affect production, a company representative said.
Pemex said that three workers were exposed to hydrogen sulfide released during maintenance of one of the refinery's diesel plants. One of the three died.
The Madero plant, the smallest of Pemex's six domestic refineries, is near the port of Tampico on the Gulf coast and can process as much 186,000 barrels of crude oil per day.
Reporting by David Alire Garcia; Editing by Tom Brown and Lisa Shumaker