Brave commuters on the Elizabeth Line came to the rescue of a fellow passenger who was being slapped and insulted by a feral stranger - before forcing the attacker to apologise.

Stomach-churning footage shows an unidentified man slapping another passenger on board a service from Forest Gate towards central London on Thursday.

Wearing sunglasses, he can be heard hurling insults before hitting the man on the face and beginning to walk away.

However, other passengers then rush to the victim's defence - with one fearless woman shouting 'leave him alone, get off the f***ing train'.

Another male passenger says 'why did you hit him?' to which the attacker responds 'because he was in my way.'

The attacker then apologises to his victim after concerned bystanders insist he say sorry, before then calling his victim a 'f***ing c***' and walking away.

He later alighted at Stratford station in east London.

Passenger Julia, 35, said the aggressor had 'stomped past' her before getting to the young man, and telling him 'move out the way' despite there being plenty of space, prompting her to record.

The 35-year-old, who was on her way to an event in central London, praised passengers' intervention to stand up for the victim as 'brilliant'.

The Miami local said: 'Especially the woman who was screaming, good on her – I think she sounds like a brave woman who maybe has stood up for other people before.

'It was like a domino effect, which was good – because then you have three or four dudes standing up and demanding he apologise.

'It was nice to see that.'

Julia said she texted British Transport Police on its 61016 service, but received no response.

British Transport Police says it tried to call her 'a number of times' but was unable to get through.

On Reddit, commenters praised passengers for standing up to the man.

One user said: 'When you see something wrong, say something. The world would be a lot nicer to live in if we had each other's back.'

Another wrote: 'God bless the woman that started the reaction.'

In a statement, a British Transport Police spokesperson said: 'Officers were contacted at around 12.40pm on Thursday 18 June to reports of an assault on an Elizabeth Line train.

'The suspect left the train at Stratford.

'Officers responded and searched the area but the man was not found.

'Enquiries are ongoing. Anyone with information that could help police should text BTP on 61016, or call 0800 40 50 40, using the reference 370 of 18 June.'

Transport for London was contacted for comment.