JAKARTA, Indonesia — Four foreign inmates have escaped from a high-security prison on the Indonesian resort island of Bali after digging a 50-foot tunnel under the prison’s walls, the authorities said on Monday.

Prison guards and local police officers found the tunnel around 8 a.m. local time, leading to a road outside Kerobokan Prison, which houses more than 1,000 inmates, including a large number of foreigners convicted of crimes including murder and drug offenses.

The prison, which is west of Denpasar, the island’s capital, is only a few miles from many of Bali’s internationally famous beaches and resorts.

The police said that the entrance to the tunnel was only 20 by 30 inches. Initially, the authorities thought that as many as seven prisoners had escaped, but a count confirmed that it was only four.