It happened at 10.15pm on Sunday as the two men, in their 20s and 30s, stood outside the Two Brewers pub on Clapham High Street.

They were approached by a man who attacked them with a knife before running away.

Both men were taken to hospital for treatment and have since been discharged, the Metropolitan Police said.

The incident is being treated as a homophobic attack and enquiries are ongoing to locate and arrest the suspect, the force added.

Giancarlo Galliani, 34, was inside the pub when the attack happened.

"I think it's really serious and quite scary," he told Sky News.

"At the time we weren't aware that it was a homophobic attack. The fact it might be targeted is really quite frightening."

Jordan Pollard, who performs a drag act at the pub but was not there this week, said there was another attack at a different bar nearby about a month ago. That incident was also deemed to be homophobic, he said.

Detective Inspector Gary Castle said Scotland Yard is "acutely aware of the shock this attack will cause members of the LGBT+ community".

He added: "We recently announced the reinstatement of LGBT+ community liaison officers for each of our 12 basic command units (BCUs) in London to support and advise on investigations where homophobia is a motive, and to ensure the community has a dedicated point of contact to address any concerns they may have."

A spokesperson for Two Brewers, a gay bar and nightclub, said they are "fully supporting" police in their investigation regarding the "unprovoked attack".

"Our thoughts are with the victims and their families," they said.

"We would like to reassure the LGBTQIA+ community that the safety and security of our guests remains our number one priority, our CCTV has been handed over to the police and enhanced security measures have now been put in place."

Amy, who is 35 and lives in Clapham, was a passenger in a car driving past the Two Brewers just after the incident.

"We saw an ambulance and police everywhere," she said.

"There was lots of commotion and lots of people. I saw a man with blood over his torso."

Her friend, who was driving, thought he saw someone being restrained.

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Drag performer Mary Mac, who was at the nightclub on Sunday, posted on social media: "It's shocking and disgusting that in 2023 this is becoming frighteningly more frequent.

"The team at The Two Brewers were incredible in dealing with this and keeping us inside the venue safe, glad the victims have been discharged and hope they are with loved ones now to help."

London mayor Sadiq Khan called the incident "abhorrent".

"It's a huge relief the victims are out of hospital - my thoughts remain with them and their loved ones. If you have any information, please do not stay silent," he said.

Any witnesses are being encouraged to contact police as soon as possible.