Indian rescue workers were trying to reach 15 coal miners trapped underground for 13 days on Wednesday as families prayed for their safe return, but chances of survival looked slim after floodwaters rushed through the illegal "rat-hole" pit.

The 15 went to work at the mine in the northeastern state of Meghalaya on December 13 and have been underground ever since.

"Only God's grace and some miracle can help them to be alive," Kyrmen Shylla, Meghalaya’s disaster management minister, told Reuters by telephone from capital Shillong.

The rescue operations was suspended on Sunday following flash floods from a nearby river, officials said.

A team of about 100 National Disaster Response Force (NDRF) experts have been camping at the mine site but their operations have been hampered by lack of sophisticated equipment, S.K. Shastri, NDRF commandant leading the operations, said.

The mine is an old, illegal so-called rat-hole mine, common in Meghalaya but dangerous as the coal is pulled out from narrow, horizontal seams.

Workers, including children, descend hundreds of feet on bamboo ladders to dig out the coal, often leading to accidents at such mines.