A mother was racially abused and assaulted on a Tube train by a woman who also threatened to have her children kidnapped.
British Transport Police said the assault took place on the Central Line at 18:30 GMT on 28 December.
The victim asked the woman, who was seated opposite, to stop swearing as she did not want her three small children to hear it.
Police have released an image of the woman who has not yet been identified.
The assault took place after the mother, aged in her 30s, and her three children, aged between two and five, got on the train at Oxford Circus station.
‘Aggressive and disgraceful’
Police said the woman became aggressive and racially abusive, shouting at the children and threatening to kidnap them in a 20-minute “torrent of verbal abuse”.
The victim got up to challenge the woman, who kicked her in the stomach before getting off at Mile End station in east London.
PC Alom Uddin said “This was an utterly awful experience for the woman and her children, who were all terrified by the woman’s aggressive and disgraceful actions.
“We will never tolerate hate crime on the rail network and are working hard to identify the person responsible.”
A passenger captured a picture of the woman, who had long, wavy, dark brown hair, and wore a dark green jacket and grey trousers.