Massive flood recovery in Spain as death toll hits 211

The deadliest flash floods in Spain's modern history have killed at least 211 people and dozens are still unaccounted for, Prime Minister Pedro Sanchez says, four days after torrential rains swept the eastern region of Valencia.

In a televised statement, Sanchez said the government was sending 5000 more army troops to help with the searches and clean-up as well as 2500 soldiers already deployed.

"It is the biggest operation by the armed forces in Spain in peacetime," Sanchez said on Saturday.

"The government is going to mobilise all the resources necessary as long as they are needed."

The tragedy is already Europe's worst flood-related disaster since 1967 when at least 500 people died in Portugal.

Volunteers flocked to Valencia's City of Arts and Sciences centre for the first coordinated clean-up organised by regional authorities.

The venue has been turned into the nerve centre for the operation.

On Friday, the mass spontaneous arrival of volunteers complicated access for professional emergency workers to some areas, prompting authorities to devise a plan on how and where to deploy them.

Rafael Armero, 19, who was in Alfafar, a suburb of Valencia, told Reuters on Saturday: "I have been going around the town for three days helping everyone who needs it.

"We have a backpack full of food and water for anyone who needs it."

More than 90 per cent of the households in Valencia had regained power on Friday, utility Iberdrola said, though thousands still lacked electricity in cut-off areas that rescuers struggled to reach.

The storm triggered a new weather alert in the Balearic Islands, Catalonia and Valencia, where rains are expected to continue during the weekend.