Police are appealing for any witnesses or information concerning a stabbing in Wetherspoons at the Elephant and Castle on Friday 11 February.
A 23-year-old Frenchman, who was visiting the UK, was having a drink with some friends inside the pub. He went to the gents toilet where he was suddenly attacked by a man who stabbed him three times.
The victim tried to ward off his attacker and managed to take the knife away from him. Unfortunately, at this point, other members of the public entered the toilet and began to attack the victim; he was holding the knife and they believed him to be the suspect instead of the victim.
The incident began to spill out on to the nearby street and the suspect was able to escape.
The victim received serious injuries, including a punctured kidney and a wound that missed his lung by a fraction. He was taken to a local hospital and received emergency treatment. As soon as he was able to travel, he returned to France where he is still receiving medical attention.
The suspect is described as a white man with slightly tanned skinned, probably aged in his mid 20s, of thin build and carrying a rucksack.
"We have spoken to some people who were in the pub that night but we are still keen to trace any further witnesses, especially anyone who was in the toilet and saw anything of the incident," said DS Jane Corrigan of Walworth CID.
"The victim has no idea why the man attacked him; he did not know him and he was not robbed."
Police are examining CCTV footage taken from inside the pub and around the area.
Anyone with any information should contact DS Corrigan at Southwark CID on 020 7232 6277, or Crimestoppers on 0800 555 111 if you wish to remain anonymous.