A man was stabbed while travelling on a Central Line train on the London Underground, police said.
The incident happened between Stratford and Mile End at about 12.50am on Sunday morning, British Transport Police (BTP) said in a statement.
Witnesses on social media said the man was "stabbed in the face" after an argument with a man near to him on the train.
Photos shared online by witnesses show the victim following the attack and a blood-soaked newspaper on the floor by passengers feet.
A woman called Rukshana on Twitter wrote on Sunday morning: "A man just got stabbed in the face on the Central Line between Mile End and Bethnal.
"I didn’t see who it was apparently it was a man sitting near him they were arguing can’t believe it!
"Hope he’s okay."
In a later tweet she added: "... never seen something so horrible in my life blood everywhere."
Paramedics from the London Ambulance Service treated the victim for injuries which are not believed to be life-threatening.
Police have released a CCTV image of a man they would like to speak to in relation to the investigation, and are also urging any witnesses to come forward.
A British Transport Police spokesperson added: "Anyone with information should contact BTP by calling 0800 40 50 40 or texting 61016, quoting reference number 36 of 30/9/2018."
PA
