Bali Deputy Police Chief Nyoman Suryasta insisted that firm action would be taken against the officers, who had "damaged the name of Indonesian police, especially Bali police".

The claims of serious corruption are expected to cause further embarrassment for Bali's police force and cast a shadow over the island paradise that attracts thousands of Australian tourists each week.

Just a day before the officers accepted blame for the corruption, the chief of Kuta Police Deddy Januartha had called a press conference and emphatically denied any of his officers had taken bribes.

He attempted to support the claim with a handwritten statement, which was purportedly signed by members of the buck's party and apologised for hiring a stripper at an upmarket Seminyak restaurant in February.

"I am so sorry for what happen and I prom (sic) that it will never happen again. I did not pay any to for police (sic)", the letter stated.

But in an extraordinary backflip, an investigation by Indonesia Police's intelligence and crime departments found that money had been paid to Kuta police, who had made admissions.

"We investigated and we confirmed it's true, it really happened, there were facts," Mr Nyoman said. "We have reported this to the Indonesian Police Chief. We will take firm action."

He said the seven officers had admitted wrongdoing. They said the bribe was less than $25,000 but "clearly they have broken the ethical profession code".

Mr Nyoman said the Kuta Police Chief had been questioned as a witness but the information thus far suggested he had not been involved.

He said the internal investigation was launched after the Indonesian Embassy in Australia reported a strong backlash on social media when Fairfax Media revealed the corruption allegations in June.

Yesterday, a member of the buck's party who asked not to be named, said he had no confidence the Indonesian police force or justice system would punish the officers involved.

"It will be a white-wash. I doubt anything much will happen and they'll probably get a slap on the wrist," he said.

"I'm actually surprised they've investigated this properly and at least it's caused some embarrassment for the police over there".

The man denied signing an apology letter, which he claimed had been fabricated by Balinese police to "cover their arses".

The group, which included nightclub owner Nick Russian and celebrity hairdresser Joey Scandizzo, visited Bali in February for the buck's weekend of marketing consultant and former model, Mark Ipaviz.

Mr Ipaviz did not return calls from Fairfax Media yesterday, but is believed to have received offers from commercial television networks for his story.

According to two men who attended the dinner in Seminyak, a decision to hire a stripper had prompted a raid by private security guards brandishing guns.

One of Mr Ipaviz's friends was hit over the head with a bottle, several were shocked with Taser guns, while another was pistol-whipped and threatened with death.

The 16 men and the stripper were bundled into vans and taken to a police station holding cell in Kuta, until a translator arrived in the morning.

"She [the translator] was negotiating with two of Mark's mates and made it clear that we should not call the consulate, because that would stop any negotiations and we'd spend months in prison before any trial. She said we could pay a fine and it would all be sorted," said a source.

After more than 24 hours in custody, two men were dispatched to withdraw about $250 million Indonesian rupiah (more than $A25,000) on behalf of the group from ATMs while chaperoned by the translator and an armed police officer.

Once the bribe was paid, the group was released, but missed their return flights to Melbourne.