Prison officers became aware of the escape while conducting a morning check of inmates at the Kerobokan penitentiary in Bali's capital, Denpasar, said Putu Ika Prabawa, an officer at Bali's Kuta Utara police station.
"It seems that they have escaped through a 50 x 75cm (20 x 30 inch) hole at the prison's outer wall which have led to their escape", Bali police spokesman Hengky Widjaja told AFP.
Of the other escapees Bulgarian Dimitar Nikolov Iliev was jailed for seven years for money laundering, Sayed Mohammad Said was jailed for 14 years on drug charges and Malaysian Tee Kok King bin Tee Kam Sai was jailed for seven years on drug charges.
Increased checks in the airport, port and bus terminals are being launched to apprehend the prisoners, who include Australian Shaun Edward Davidson.
The four escapees were serving sentences for different crimes.
"We will investigate if someone helping them from the outside".
The tunnel is just 40cm in diameter and ran from behind the jail clinic, under the jail wall to the outside, ironically just near the guard tower.More news: Van hits pedestrians in London, 'number of casualties' reported
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Some reports said it was an existing tunnel used for water drainage.
Davidson, 32, from Subiaco in Perth, was convicted of using another man's passport in Bali.
He's also wanted in Perth, Australia for drug charges and reportedly left the country for Indonesia on the same day that he was due to appear court.
The police are now hunting down the inmates.
And inmates in their prison block were being questioned.
Bali prisoners broke out in Great Escape style.
He said the great escape is believed to have taken place on Sunday night when there were 10 guards on duty.
"We have spread the photos of those foreign inmates that have escaped and we are chasing them now", he said.