Police are appealing for witnesses after a man is said to have attacked a Tube passenger and verbally abused several others.
The reported incident happened on New Year's Eve at around 2:45pm on board a Central Line train travelling from Stratford to Redbridge station.
A female passenger said she intervened when she saw a 26 year-old man assault a man and abuse a woman in the same carriage.
She then claims to have been subjected to abuse and threats by the man.
The suspect was removed by police at Redbridge station and arrested on suspicion of committing a public order offence.
He has been bailed until February 12 pending further enquiries.
Detective Constable Martin Wilson, of British Transport Police (BTP), is urging witnesses to come forward.
He said: "Enquiries are ongoing to establish the full circumstances surrounding the incident and, at this stage, I am appealing for anyone who was on board the train at the time to come forward with information about what they saw."
Anyone with information should contact BTP on 0800 40 50 40, or Crimestoppers anonymously on 0800 555 111.