Four foreign inmates have escaped from Kerobokan prison on the Indonesian resort island of Bali using a tunnel, the head of the prison said on Monday.

Tony Nainggolan named the four as Australian Shaun Edward Davidson, Bulgarian Dimitar Nikolov, Indian Sayed Muhammad and Malaysian Tee Kok King.

"The tunnel is about 12 meters (39 ft) long and we suspect it took more than a week to build," Nainggolan said, adding that police had launched a search and believed the men were still in Bali and not far from the prison.

By Reuters.