A mother was assaulted on the subway in New York after her child asked her a question about another youngster on the train, police say.

The victim, who has not been identified but is aged 50, was riding a Queens-bound E Train on November 2 when the attack happened around 1.30pm.

Police say the attack started when her eight-year-old son asked why another child on the train was wearing a costume.

A 50-year-old mother was hit in the head and placed in a chokehold on a Queens-bound E Train after her eight-year-old child asked why another youngster was wearing a costume

At that point, the second child's mother - who is African American - became upset, saying 'tell your f***ing son not to disrespect my child', the New York Post reports.

Officers say this suspect, aged somewhere between 25 and 30, put the mother in a chokehold during the fight

Video put out by the NYPD shows a heated argument between the two women, though there is no sound recording.

The aggressor can be seen slapping the other woman in the side of the head, before hitting her repeatedly in the head with her phone.

Police say another suspect, also an African American woman who can be seen in the video in a red hat and blue coat, then put the victim in a chokehold.

Both of them fled the train after the assault at the 71 Street-Continental Avenue station and are being hunted by officers.

The first individual is a female, black, 25 to 30 years old, with eye glasses; last seen wearing a gray shirt, dark colored pants, a black jacket tied around her waist and she had a black purse over her shoulder.

The second individual is a female, black, 25 to 30 years old; last seen wearing a red baseball cap, a blue jacket and gray sweatpants.

Officers are investigating but have not arrested either of the two suspects.