A man's nose and eye socket were fractured during a robbery in Castle Park.
The victim, a 25-year-old Chinese man, was walking alone through the city centre park on July 22.
At around 12.20am, four men surrounded him and then knocked him to the ground.
His wallet was stolen by the men and his bank card was used later in a shop in Old Market and a number of other transactions.
The victim has since returned home since the incident.
He describes his attackers as four as black men aged between 18 and 20.
One was riding a bicycle. Two were about 5ft 8ins tall while the other two were shorter.
CCTV images have been released of two men officers want to trace in connection with the incident.
Avon and Somerset Constabulary is appealing for anyone with information to come forward.
A police spokesperson said: "We’re asking for help to trace these two men as part of our investigation into a robbery in Castle Park, Bristol.
"If you have any information which could help the investigation, get in touch, quoting reference 5219166953.
"If you can help, please call 101 and give the call handler the reference number 5219166953.
"You can contact the independent charity Crimestoppers 100 per cent anonymously on 0800 555 111 or via their Anonymous Online Form.
"No personal details are taken, information cannot be traced or recorded and you will not go to court or have to speak to police when contacting Crimestoppers."
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