An ambulance was called to treat Frost,who was suffering bruising and redness on his face.
A police spokeswoman said the"younger man"– Frost – was searched in the ambulance before being taken to hospital and allegedly found with a knife,which was seized.
On Tuesday afternoon the band posted an uncaptioned image of Cornwall and Frost together,but otherwise declined to comment.
Police are continuing to investigate.
Asked about the alleged fight,Marrickville Bowling and Recreation Club manager Tommy Jones said he had"no idea about anything to do with it".
Sticky Fingers have a turbulent history. The band shot to prominence in the early 2010s,recording several well-reviewed albums and touring internationally.