Sex workers striking for better pay, a cleaner workplace and the right to decide which services they provide to clients at an upmarket inner Sydney brothel have been met with an alleged aggressive response, according to protesters.

Seven of the Penthouse club’s sex workers picketed and delivered signed letters to the business late on Friday night, demanding fairer workplace conditions. One, a 21-year-old, was allegedly assaulted inside the venue while carrying a placard.

Penthouse bills itself as “the only 6 star brothel located in Sydney CBD”.

Sex worker and former Penthouse contractor Iris Hues said the club changed its pricing structure and service menu at the beginning of the month, raising rates without increasing workers’ earnings, as well as penalising workers with hidden fees and fines.

She said that while some demands had been met, others – including reinstating the former 60/40 sex worker/business earnings split – had been ignored, forcing the women to take strike action.

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Shortly before midnight on Friday, protesters approached the front desk of the club, holding signs that read “No profit without u$!” and “Worth more than 50/50”.

The letters’ 14 signatories also alleged the club failed to provide a clean workspace, blaming unhygienic conditions for a spate of respiratory illnesses, including pneumonia.

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“Today, we walk out – until our needs are met,” they wrote. “You raise your cut on extra services we provide, without a raise for the ones providing it. Dictating the services we provide, taking away our choice with our own bodies.

“The reason we worked here was because we felt comfortable, and now we feel controlled.”

After the women delivered the letters to the front desk, they entered the club’s main bar area where, in front of about 40 patrons and sex workers, one of the women was allegedly assaulted, Guardian Australia was told by multiple witnesses.

New South Wales police said that following reports of an alleged assault at a business on Pitt Street, officers “were told an altercation had occurred between a group of people and a man, before the group left the scene. Investigations are ongoing.”

Hues claimed she was fired last week from the Penthouse for raising concerns around work conditions. She claims all seven protesters had now lost their contract positions at the club.

“We were all shaking before we went in. It was really, really scary,” Hues said.

“We didn’t get to communicate or open a dialogue with management at all.”

She said about 50 women worked at the club, but that many felt unsafe to strike.

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“There is a large portion of girls that can’t afford to not work, or can’t afford to go and find another brothel,” she said.

“The power imbalance has been in the favour of the pimps and the bosses for too long, when the sex industry has always belonged to its workers. We make them their money. The sex industry thrives on silence and us not being able to say or know anything.”

The protest was modelled on direct action taken by strippers as part of New Zealand’s Fired Up Stilettos movement and Sydney’s 1973 Kings Cross stripper strike, she said.

The Scarlet Alliance’s chief executive, Mish Pony, said that as sex work was decriminalised in more jurisdictions across Australia, sex workers increasingly had the ability to organise and strike over workplace health and safety and pay conditions without legal repercussions.

She said earnings splits usually varied from 40/60 to 60/40.

“It really is dependent on the venue. And because sex workers are generally treated as subcontractors, there is no blanket rule on protections for sex workers,” Pony said.

She said sex workers had full rights of refusal to perform a sex act.

“Although these issues are very disappointing to hear about, it’s also very heartening to know workers are coming together and fighting for workplace rights,” she said of Friday’s protest. “Nobody should be forced to put up with bad workplace conditions.”

The Penthouse has been contacted for comment.