The New South Wales police union has called for more detectives to be based at Redfern amid revelations that there is only one officer assigned to investigate robberies in the area.

Two local policeman who are union representatives have told a parliamentary inquiry the station has inadequate resources.

The inquiry has been told about a series of violent attacks on elderly women in Redfern over the past few days.

Detective and union representative Frank Reitano told the hearing there is only one detective at Redfern.

"As of today we have one officer who is investigating robberies at Redfern [and] he's a very junior officer," he said.

Fellow officer Paul Huxtable also told the inquiry: "These are violent street robberies, we have a situation at Redfern where criminals are walking freely in the street and the residents are locked behind doors with bars on the windows."

The union has described staffing levels as woeful and wants a dedicated robbery unit to be established.