Dozens of rescuers tried to reach the trapped men, but rock slides and a mix of gas and coal debris forced them to resurface after four hours of digging, district police Chief Yasman Esha in West Sumatra province said by phone from the scene. We fear the miners are dead by now,' Mr Esha said.

Four bodies were recovered soon after the morning blast at the 300-foot (100-metre) -deep mine in Sawahlunto regency on Sumatra island, he said.

Police said methane gas ignited in the mine, causing a massive explosion that left a crater about 100 metres (330 feet) deep.

Health Ministry Crisis Center chief Rustam Pakaya said 14 miners were rescued, but five with severe burns died later in a hospital. Two others were in critical condition, he said.

Police were trying to determine what caused the blast. A preliminary investigation said it was triggered by leaking methane gas.

The mine is 560 miles (900 kilometres) northwest of the capital, Jakarta. Owned by a group of residents, the miners were using traditional methods, with little or none of the mining safety measures required by law in most countries, Mr Edward said.

'According to witnesses there was an explosion caused by methane gas. Methane gas is the main threat to local miners and there have been several explosions before,' he added.

The blast was heard 1.5 kilometres (about a mile) away and sent flames 50 metres into the air, local government official Syafriwal told ElShinta.

Some of the survivors were severely burned, hospital staff said. -- AP, AFP