This is despite the territory government recommending the measure to combat sex slavery during a 2011 review of its own prostitution laws.

Raids on Fyshwick escort agencies this week led to an Australian woman being charged and five Thai nationals detained over immigration offences. Court documents said police had seized items of interest in relation to "potential future human trafficking and/or forced labor offences".

Border Force would not comment on whether the five Thai women would be deported.

Earlier in the year, a former Canberra brothel owner was extradited to the ACT and charged with a string of offences, including human trafficking, after allegedly posing as a woman to lure women to Australia to work as escorts.

In a submission to a 2011 review into Canberra's sex work laws, the ACT government said there was an "internationally recognised link" between the sex industry and labour trafficking.

"The government supports making it compulsory for all brothels in the ACT to have multilingual signs on display in prominent places, clearly stating that slavery is a serious crime," it said.

The recommendation received the backing of the full committee examining the Prostitution Act 1992, further calling for a 24-hour, seven-day hotline to report such offences. Victorian brothels are required to display such signs in English, traditional and simplified Chinese, Korean, Russian and Thai.

But proposed amendments to the ACT's existing legislation tabled in the Legislative Assembly in June did not address the recommendation. A Justice and Community Safety Directorate spokeswoman this week confirmed it would not be revisited despite recent events.

The spokeswoman said the bill's working group - made up of the Justice and Community Safety Directorate, ACT Policing, the Scarlet Alliance, the AIDS Action Council (including its Sex Worker Outreach Program) and the Human Rights Commission - was unable to reach consensus on the proposed signs.

Concerns included that the proposed requirement singled out the sex industry, noting other industries battled the same issue; that the signs would stigmatise sex workers; and the possibility that some clients might threaten to report people trafficking "as a means of placing a sex worker under duress in order to obtain services that would not otherwise be offered".

Human trafficking issues were "handled expertly by the Australian Federal Police and Australian Border Force", the Justice and Community Safety Directorate spokeswoman said.

"As this week’s raids demonstrated, the ACT government has a good cooperative relationship with law enforcement and relevant regulatory agencies to keep our community and our workers safe," she said.

"Further reforms to safeguard against human trafficking would need to be done in consultation with federal agencies responsible for investigating such matters, and importantly with regard to the views of the sex work industry to ensure that the protections afforded to sex workers are appropriately adapted to their particular industry."

The AIDS Action Council said previous signage had been ineffective.

"[Sex Worker Outreach Program] ACT is developing innovative ways to engage sex workers from diverse backgrounds based on mutual respect and trust to provide appropriate support and protections for impacted workers," deputy executive director Joshua Anlezark said.

The Prostitution Amendment Bill 2018 aims to reduce stimga and discrimination faced by sex workers and promote their work health and safety.

Proposed changes include replacing references to "prostitute" and "prostitution" with "sex worker" and "sex work". If passed, sole operators would no longer have to register with the Office of Regulatory Services, brothel owners would have to provide workers with prophylactics and HIV-positive workers would be allowed to work.