Police are re-newing an appeal for public help to find a knife-wielding robber who jumped a convenience store counter stabbed a store attendant in a brutal attack caught on CCTV.

Two separate robberies in central Sydney - including one where a man was stabbed - have been linked by police, prompting the re-release of the footage on Wednesday,.

View photos The armed attacker can be seen sliding along the convenience store counter and threatening the attendant. Photo: NSW Police More

Detectives are appealing for the public’s assistance in identifying a man who may have information regarding two robberies, one in Chippendale in December and another at an Ultimo store last month.

In the footage, the armed attacker slides across a Chippendale convenience store counter located on Buckland Street at about 9.45pm on Saturday 19 December 2015.

The knife-wielding man confronts the 35-year-old attendant threatening him with a knife while demanding money.

View photos The armed robber demanded cash from the store attendant before stabbing him in the shoulder. Photo: NSW Police More

View photos The two struggle with each other inside the cage before the robber stabs the attendant and flees the scene. Photo: NSW Police More

During the attendant's struggle to survive, he attempts to fight off the robber but was stabbed in the shoulder.

Emergency services arrived at the scene and the injured man was rushed to the Royal Prince Alfred Hospital with non life-threatening injuries.

View photos This is incident which took place in Ultimo last month and police believe the attacks are linked. Photo: NSW Police More

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