The victim was approached by a man on the canal towpath near Ridge Lane Bridge at around 7.30pm on Wednesday, January 5.
He was then tackled by four other men who stole his Adidas shoulder bag and went through his pockets.
Police said the 34-year-old victim suffered a broken jaw in the vicious robbery along with "other injuries".
The offenders - who were wearing all black clothing - are described as white men in their mid-20s.
Anyone with information can contact police by calling 101 or emailing [email protected], quoting log number LC-20220105-1175.
Alternatively, independent charity Crimestoppers can be contacted anonymously on 0800 555 111 or via crimestoppers-uk.org.
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