Planinsko polje, 5 km long and 2.5 km across, is often flooded, but this year waters have risen so high due to snow melt and rainfall a dozen houses on the normally safe higher ground have been inundated.

Relief workers, firefighters as well as soldiers, have been hard at work to keep the waters away from houses. They have installed over 5,000 sandbags and are pumping water out from behind the makeshift dams.

But despite their efforts at least two dozen houses are still at risk of flooding. The water level is expected to rise by another 40 centimetres over the weekend, the local fire brigade said Friday.

So far over a dozen families have been evacuated to nearby Postojna and livestock has been transferred to higher ground.

Planinsko polje is a flat plain characteristic of karstic regions and is connected by swallow holes with several similar neighbouring depressions.

However, since its altitude is lower than that of its neighbours, it has been taking on water from farther afield than usual, with the inflow far exceeding its drainage capacity.

Cave divers have inspected the drainage following reports that hay bales have blocked the water, but the results of their work have not been made public yet.