An NYPD sergeant was kicked off a Greyhound bus in Philadelphia because the driver thought the officer was too drunk to ride, cops said.

The driver told off-duty Sgt. Carlos Fabara to get off the New York-bound bus, said witness Geoffrey Parrish, an actor who lives in Park Slope, Brooklyn.

Internal Affairs is probing Fabara’s actions and whether his traveling companion was another NYPD cop, a police spokesman said.

“It was pretty obvious they were hammered,” Parrish said.

The driver called security but the stubborn sergeant refused to disembark, and it took a Philly cop to handcuff Fabara and take him off the bus, Parrish said.