Police are ramping up the search for two men involved in a random, drug or alcohol-fuelled attack on a cyclist at Prahran.

The cyclist was at the intersection of Chapel Street and Malvern Road about 8.15pm on June 8 when he was set upon by two men who appeared to be under the influence of drugs or alcohol.

A 28 year old passer-by has intervened before he was also attacked, suffering minor facial injuries.

Police have today released images of two men wanted for questioning (pictured above).

Both Caucasian in appearance, one man was wearing a distinctive blue and white Fila top.

The other was wearing a black jacket.

Police are also hoping to speak to the cyclist who left the scene before officers arrived.

Anyone with information or who recognises the pair is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au