Two Rikers Island officers have been indicted in the beating of an inmate and subsequent cover-up, authorities said Tuesday — the latest bust in a years-long probe into the violence-plagued city jail.

Officer Sean Smith, 41, is charged with grabbing a female inmate by the hair and punching her “repeatedly in the head,” the Bronx DA’s office said.

The March 2014 incident inside the jail’s Rose M. Singer Center escalated after detainee Shandra Brown, who was on suicide watch, was given a smock to prevent her from hurting herself, authorities said.

After Brown tore off her smock and threw it at Smith, the officer attacked her, prosecutors said.

Fellow officer, Velma Rogers, 55, allegedly watched the assault — but did nothing, authorities said.

Neither officer filed a “use of force” report, required of any correction officer who uses force on an inmate, officials said.

After the inmate alleged that she had been assaulted, investigators asked both officers to file reports about what happened.