The FDP (Liberal) party has slammed the costs of the barrier, staffed by security guards at night, which amount to 20,000 francs ($21,000) a month.
The barrier was installed in conjunction with a regulation, passed by parliament in May, that allows prostitutes to offer their services only until 2am.
But the Tages Anzeiger newspaper, citing a report from consumer publication Beobachter, says Marco Zolin-Meyer, an FDP politician in the nearby municipality of Uetikon, owns with his wife the building housing the district’s biggest brothel.
With prostitutes paying 106 francs a day to use rooms in the building on the Zähringerstrasse, the total rental income reportedly amounts to up to 65,000 francs a month.
The street has long been known for its prostitutes although hotels, residents and businesses have recently lobbied for changes.
A resident said the situation became “unbearable” two years ago when women from Eastern Europe moved into the building owned by Zolin-Meyer, Tages Anzeiger reported.
Rooms were repartitioned and rented for “erotic services” while the loft was expanded without a proper permit, the newspaper claims.
The city’s fire prevention and engineering departments are investigating the situation.
The couple who reportedly own the building have declined to comment.
Marc Bourgeois, FDP city councillor, has been outspoken in his criticism of the red-light district barrier, complaining of its expense and its disruption of traffic.