Four police officers have been put on restricted duties following reports they were involved in a fight while off-duty.
The Metropolitan Police received several calls at around 11pm on 1 December after people were seen fighting on Jubilee Bridge and by the Royal Festival Hall, South Bank, in central London.
Four officers allegedly involved in the brawl are no longer on public facing duties, the force said.
No arrests have been made in connection with the incident.
Police said they are keen to speak to a group of Romanian men who may have information about what happened.
They are also urging any witnesses or anyone with information or footage of the incident to contact them.
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Detective Inspector Nicholas Goldwater, who is leading the investigation, said: “Our CID team is working alongside colleagues from the Directorate of Professional Standards to ascertain the facts of the incident, which led to numerous calls being made to the police that night.
“We are pursuing all lines of enquiry to establish what happened, including viewing a large amount of CCTV footage.
“These CCTV enquiries are lengthy and ongoing.
“We would like to hear from anyone who was involved – including a group of men we believe to be of Romanian heritage – who may have information about the incident.”
The Met has made a voluntary referral to the Independent Office for Police Conduct (IOPC).