A 19-year-old man has been arrested on suspicion of attempted murder after a man was stabbed on a train in south-east London on Wednesday, British Transport Police (BTP) said.

Police received reports of two men fighting between Shortlands and Beckenham Junction railway stations shortly before 4pm on Wednesday.

Footage shared on social media showed a male wearing a black hooded jacket, black trousers and a face mask holding a large blade, while onlookers could be heard telling him to stop.

A search was launched and on Thursday BTP said they had arrested a 19-year-old man and recovered a knife.

Officers were called to Beckenham Junction station following reports of the on the train, which was heading towards Victoria. British Transport Police attended, alongside London Ambulance Service and Metropolitan Police.

The victim, who is in his 20s, was taken to hospital and is in a “critical but stable condition”.

Superintendent Darren Malpas said: “We understand the concerns of the public following this incident and our detectives have been working tirelessly to investigate. I hope this arrest will bring some reassurance to those on the rail network.

“High-visibility patrols will continue in the area and across the network as a visible reassurance to the travelling public.”

Witnesses were urged to contact police on 0800 405040, texting 61016 quoting reference 397 of 27 March or call Crimestoppers anonymously on 0800 555 111.