Police have released images of two male youths they would like to speak with after a teenager was strangled and forced to apologise for being gay.
The unprovoked homophobic attack on the London Underground also saw the 19-year-old victim threatened with being stabbed and his female friend punched to the ground.
The shocking assault happened on a westbound Jubilee Line train between West Ham and North Greenwich at around 11.10pm on 21 October.
British Transport Police say two suspects boarded the train at West Ham and began hurling homophobic abuse at the victim and his friends, who were in fancy dress on their way to an event.
When challenged, the offenders became more aggressive and detectives say one of the pair pulled the 19-year-old victim from his seat and into a headlock, strangling him.
The other suspect then allegedly took the victim's phone and threatened to stab him.
"They demanded the victim apologise for being gay which eventually the victim did as he was struggling to breathe," a spokesperson for BTP said on Monday (4 December).
"They then let him go and handed back his phone and a fight ensued between the victim's friends and the offenders."
One of the victim's friends, a 25-year-old woman, was then punched and pushed to the ground. She sustained bruises while the first victim did not sustain any injuries.
The victims left the train at North Greenwich station, police said.
"Officers would like to speak to the people shown in the images as they may have information which could help the investigation," a BTP spokesperson said.
"If you recognise them, please call BTP on 0800 40 50 40 or text 61016, quoting reference number 273 of 1/12.
"Hate crime will not be tolerated by British Transport Police. We believe that everyone has the right to travel safety.
"We won't tolerate behaviour where someone is targeted because they are perceived to be different, or made to feel uncomfortable on their journey."