WARSAW (REUTERS) - More than two dozen rescue workers are battling to save two cavers trapped in a cavern in Poland's Tatra mountains after a narrow tunnel flooded with water, blocking their exit.

A representative of the mountain rescue service said on Sunday (Aug 18) that it has not yet been possible to establish contact with the two cavers and concern is growing due to their long exposure to extreme conditions.

Rescuers are preparing to use explosives to open a route to access the two but the process will not be quick.

"The only way to get to them is through a series of very complicated pyrotechnic actions," said Mr Jan Krzysztof, head of the Tatra Volunteer Search and Rescue group, in an interview broadcast by TVN.

"We have the necessary materials, but this will take a long time," he said. "We have to be ready for work that could last days, if not weeks."

The two became trapped in the Wielka Sniezna cave, the longest and deepest in the Tatra mountains, on Saturday and rescue services were notified by colleagues who had accompanied them on the excursion, TVN reported.

The first rescue team was sent in on Saturday evening and since then two more groups, including members of the fire department in Krakow, have been dispatched, TVN said.

Additional support could come from Slovak rescuers, Mr Krzysztof told reporters.

Rescue conditions are particularly difficult due to flooding which could also endanger the rescuers, TVN reported.