There's concerns a former Prime Ministerial staffer hasn't faced charges after allegedly voice-recording sex workers.

Michael Forbes has quit as acting deputy press secretary over allegations he took compromising recordings of sex workers, and photos of women he didn't know.

A Wellington brothel complained to police last July, who found it didn't meet the threshold for prosecution.

Sex Workers' Collective regional coordinator Cherida Fraser says sometimes it's just the tip of the iceberg.

She explained more harm could occur, despite this seemingly being at the lower end of the spectrum.

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