Indonesian police are searching for four foreigners who escaped Bali’s Kerokoban Prison using a tunnel.
The prisoners were identified as Australian Shaun Edward Davidson, Bulgarian Dimitar Nikolov, Indian Sayed Muhammad and Malaysian Tee Kok King.
Prison governor Tony Nainggolan said he believed the men were still on the resort island.
Prison breaks are common in Indonesia which is dealing with an influx of people arrested for drug offences.
The four men were serving jail terms for a mix of drug and fraud offences.
They are believed to have escaped through a 50cm by 70cm hole found in the outer wall which connects to a 15m-long narrow tunnel, officials said.
Some reports said it was an existing tunnel used for water drainage.
Staff noticed they were missing on Monday morning during a routine check.
Australian Shaun Davidson had less than three months left of his sentence to service, according to the jail governor.
About 200 prisoners broke out of an overcrowded jail on Sumatra island in May after being let out of cells for Friday prayers.
Inmates had accused some guards of being violent and complained about their treatment in jail.