SYDNEY - Sydney municipal officials have paid private detectives thousands of dollars to have sex with prostitutes to gather evidence needed to shut down illegal brothels, an Australian newspaper reported Sunday.

Nine local councils have paid private investigators the equivalent of C$23,150 over the last three years to go undercover and root out the illicit trade, the Sunday Telegraph newspaper reported.

Nick Ebbeck, the mayor of Kuringai council, which is reported to have spent C$6,440 in the last month employing detectives to have sex with prostitutes, said extreme measures were necessary.

"We have to employ private investigators to actually go through with the act and come up with reports that will suffice in a court process,'' he was quoted saying

"On numerous occasions over numerous days and times they had to fulfil the act.''

He said the evidence given by the investigators was successful in closing two illegal brothels this month.

Licensed brothels are legal and relatively common in Sydney but a number of unlicensed premises operate throughout the city. Some councillors have complained the burden of proof for shutting down illegal brothels is too high.