An MTA employee was arrested on the job Tuesday after he allegedly smacked a cop when he was confronted for fare evasion at a Queens subway station, law enforcement sources said. 

Richard Louis, 35, allegedly slipped through a subway emergency exit without paying at the Myrtle-Wyckoff Avenue L/M station in Ridgewood Tuesday and was met by police on the other side, according to sources. 

When the cops tried to stop the worker he erupted — allegedly slapping one their hands and refusing to comply with instructions, sources said. 

Louis, who works as a light maintainer, was charged with theft of services, avoiding payment for transportation services, obstructing government administration and resisting arrest, police said. 

Once he was cuffed, Louis told police he was an MTA employee, sources told The Post. 

The arrest came a day after the NYPD announced it will flood the subway system with 800 more cops to crack down on fare-evaders, with the department claiming the initiative stops violent crime.

The MTA said Louis is suspended pending an internal investigation.