Why won't police release the CCTV footage?

Last week four men bashed a young man outside a Melbourne nightclub. Two of the suspects have been charged, but two are still at large. Police have CCTV footage which could help identify these men but refuse to release it. Why?

The Herald Sun revealed today not only that the perpetrators were Africans but that police are avoiding publicising crimes involving ethnic minorities:

Police would not release CCTV footage of the attack or details of where it occurred despite some of the perpetrators still being at large late last week.

Sources have told the Herald Sun senior police do not want publicity regarding crimes involving minority (ethnic) groups because it could inflame race debate.

Victoria Police denied this.

If the information is correct it is disturbing as it means that the police are so intent on diverting attention away from crimes committed by African refugees that they're willing to compromise criminal investigations to do so.

The Herald Sun seems to have decided not to cooperate with the cover up. It has revealed that Africans are the suspected perpetrators not only in the bashing mentioned above, but in the one that occurred at Noble Park station on Saturday night (leaving one commuter with a fractured skull and another with a broken jaw) as well as a bashing at Sunshine station last year.

Doesn't the public have a right to know?