A pregnant woman and a man were subjected to "extremely aggressive" abuse on board a train at London Bridge, police have said.
British Transport Police (BTP) has released images of a woman they wish to speak to in connection with the incident which took place this week.
The verbal attack happened on the 7.48am Southern service travelling between London Bridge and Victoria on Monday (March 27).
A woman was seen acting aggressive and swearing towards a pregnant passenger who decided to get up and move towards another carriage, the police said.
The abuse continued, at which point a 42-year-old man who observed the incident intervened.
He asked the female to stop hurling abuse at which point the suspect allegedly towered over him and shouted violent language at him.
The incident lasted several minutes, the BTP said.
Police have urged anyone who may have been travelling on the service and saw or heard anything to get in touch
Officers are also keen to locate the person in the images that have been released.
Investigating officer, PC Chris Abbott, said: “The behaviour of this woman was extremely aggressive and whilst she was not physically violent, her abuse would have been very frightening to the victim.
"No one should ever be subjected to this type of threatening and disgusting abuse and we have a number of active enquiries in place to trace the woman responsible.
“I would like to hear from anyone who might recognise the person in the images which we have released.
"Any information no matter how small could be vitally important to our investigation.”
Anyone with information should send a text message to 61016 or call 0800 40 50 40 quoting reference 91 of 27/03/2017.
Alternatively, Crimestoppers can be called anonymously on 0800 555 111.
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