A member of the group, whose ages range from 19 to 35, told the Press Association from their cell, under condition of strict anonymity, that they were confused over their arrest.
A Cambodian Police website published photographs online, appearing to show clothed and laughing tourists demonstrating sex positions.
The prisoner claimed none of those arrested were in the photographs.
Most of the group were described by police as expats – but some were travellers, including a British tourist who claimed to have been in the country just two weeks when he was arrested.
The prisoner said they were manning the barbecue at a villa party on Thursday at 4pm local time when police arrived and began picking out revellers from the crowd.
“Honestly, it was really confusing. Everyone was confused. They raided, rounded us up – there was about 80 to 100 people at this party, some of them were tourists. There were about 30 of them [police officers.]”
They said they did not understand why they were being arrested, saying they saw one of the men vomiting in shock.
The group arrested confirmed their identities, They include five British men; Vincent Harley Robert Hook, 35, Daniel Richard Leeming Jones, 30, Thomas Alexander Jeffries, 22, Billy Stevens, 21, and Paul Francis Harris, 32.
Job Robertus van der Wel, from The Netherlands, 22, Canadians Jessica Drolet, of Ottawa, 25, and Eden Koazoleas, 19, of Alberta, were also arrested, along with David Nikolaus Aleksandr Ballovarre, of Oslo, Norway, 22, and Paul Martin Brasch, 32, of New Zealand.
They said they had been assigned a Cambodian lawyer, and were due in court on Sunday.
The police website pictured a group line-up, which the prisoner confirmed to be the detained group.
A Cambodian Tourist Police officer was unable to confirm any further details at the time, when contacted by the Press Association, mentioning only that the British ambassador had called.
The Foreign Office confirmed they were in contact with British nationals in Cambodia, this evening.
“We are assisting five British men arrested in Cambodia and are providing support to their families,” a statement said.
The group confirmed during the call that all of their embassies had been in contact, and were helping the foreign nationals and their families.
They said their lawyer told them they could face up to a year in prison, and that they could be detained on a six-month waiting period if the case went to trial.
The prisoner said from their makeshift cell on Saturday that their families were “worried sick”.
“Our parents are doing what they can. It’s really just trying to keep a good vibe until we know the outcome.”
They said they have been sleeping on the floor of an office at a police station in Siem Reap for three days, and emphasised they had been treated well by their captors – saying officers were friendly and had brought them pizza.
An official Cambodian Police statement posted online on Saturday afternoon (GMT) referenced pornography and dancing in publicising the arrests, naming 10 suspects, who had been charged following an investigation by the Office Combating Human Trafficking and Protection of Juveniles.
The prisoner said the group believed the investigation was targeting foreign expats in the south-east Asian country over foreign tourists and expats wearing bikinis in public, and in relation to expat-run pub crawls in Siem Reap.
“We’re innocent,” they said. “We don’t know why we’ve been arrested – we’re getting different stories from different people.”