Rescuers raised the death toll in Spain’s worst floods for a generation to over 205 as the government deployed more troops in an increasingly desperate search for survivors.

The floods that have tossed vehicles, collapsed bridges and covered towns with mud since Tuesday are the European country's deadliest such disaster in decades.

The Organisation Coordinating Emergency Services in the hardest-hit Eastern Valencia Region said 205 people had been confirmed dead there.

Rescuers equipped with drones and sniffer dogs waded through water and rummaged through debris in search of the dozens of people the authorities believe are still missing.

The Government is deploying an extra 500 troops to the stricken areas to bolster the 1,200 already on site for search, rescue and logistics tasks.

Some cut-off areas remain without water, food or power three days after the floods began, and many roads and rail lines remain inaccessible, raising fears the death toll will climb.

According to national weather service the town West of Valencia City recorded 491 mm of rain in just eight hours on Tuesday -- almost equalling a year's worth.