Four prisoners escape from Kerobokan jail in Bali

Prison guards found a small 50cm by 75cm hole behind a clinic at the prison where they are alleged to have escaped

One of the men, Australian Shaun Davidson, 33, had less than three months left on his sentence after he was jailed past year for violating immigration law.

"We will investigate if there's involvement from other prisoners or guards", Mr Nainggolan said, with police adding that they were also looking into whether the men received any help from the outside.

Police said immigration and airport authorities had been alerted and a manhunt was underway.

Davidson's photograph, along with his three fellow escapees have been circulated around Bali as police attempt to find the men.

The others who escaped were Indian, Malaysian and Bulgarian, all convicted of drug trafficking and serving between seven and 14 years in prison, Nainggolan said.

It is believed they escaped through a hole in the ceiling of their block and then squeezed through the waste tunnel, which was 13 metres long and just half a metre wide.

Andrew Chan and Myuran Sukumaran, the alleged ringleaders, were executed by firing squad in April 2015 despite pleas for mercy from their families, who said the two men had been "fully rehabilitated" after nearly a decade in prison.

In an interview with Fairfax Media between the bars of a holding cell at Denpasar District Court last September, Davidson said the conditions in Kerobokan were bearable if one had money and support from the outside.

"It was built for 300 people, there is 1200 there". They don't give you any food, they don't give you a bed.

Despite overcrowding in Kerobokan, he said it wasn't the "living hell" he thought it would be.

Mass escapes are not uncommon in Indonesia, and reports of brutal beatings and abuse by guards are widespread.

The prison's governor confirmed he fled the Indonesian prison on Monday morning, according to 9 News.

Related News: