Police are searching for a woman who slapped a 70-year-old woman in the face after a heated argument on a northbound 6 train Friday afternoon.

The conflict began around 2:23 p.m., when the woman whom cops are seeking boarded the train at the 68th Street station, sat next to the victim and repeatedly bumped her with her elbows, according to the NYPD.

The straphangers started quarreling with each other after the older woman moved to another seat, police said. Their argument escalated to physical violence after the younger woman approached and slapped the victim in the face, a video of the incident shows.

The younger woman attacked a second time, the footage shows, after the victim sought to return the blow and kick her assailant away. On camera, an onlooker intervenes in the fight.

Two stations later, the younger passenger fled the train at 86th Street. The older woman disembarked and reported the incident at the 96th Street station.

She was treated by paramedics for pain and swelling to her face and head, but refused any other medical assistance.

Anyone with information about the attsack is encouraged to call Crime Stoppers at 800-577-8477. All callers will remain anonymous.