A 25-year-old man was slashed in the face in an unprovoked attack inside a Harlem subway station on Monday night, police sources said.

The victim was on the northbound 2/3 platform of the 135th Street and Lenox Avenue station when he was attacked by an unknown man at about 8 p.m., sources said.

The suspect fled the scene after the attack, sources said. He remained on the loose later Monday night.

The victim was hospitalized. His condition was not immediately known.