(AFP) - Spain is deploying 10,000 more troops and police officers to the eastern Valencia region devastated by historic floods that have killed 211 people, Prime Minister Pedro Sanchez said on Saturday.

Hopes of finding survivors were slim more than three days after torrents of muddy water submerged towns and wrecked infrastructure in the European country's worst such disaster in decades.

Almost all the deaths have been recorded in the Valencia region, where thousands of security and emergency services personnel were frantically clearing debris and mud in the search for bodies.

Sanchez said in a televised address that the disaster was the second deadliest flood in Europe this century and announced a huge increase in the security forces dedicated to relief works.

The government had accepted the Valencia region leader's request for 5,000 more troops and informed him of a further deployment of 5,000 police officers and civil guards, Sanchez said.

Spain was carrying out its largest deployment of army and security force personnel in peacetime, he added.

- More deaths expected -

Restoring order and distributing aid to destroyed towns and villages -- some of which have been cut off from food, water and power for days -- is a priority.

Authorities have come under fire over the adequacy of warning systems before the floods, and some stricken residents have complained the response to the disaster is too slow.

"I am aware the response is not enough, there are problems and severe shortages... towns buried by mud, desperate people searching for their relatives... we have to improve," Sanchez said.

In the ground-zero towns of Alfafar and Sedavi, AFP reporters saw no soldiers while residents shovelled mud from their homes and firefighters pumped water from garages and tunnels.

"Politicians promise a lot, help will come when it comes," said Mario Silvestre, 86, a resident of Chiva where gaping sinkholes risked triggering the collapse of buildings.

Authorities in the Valencia region have restricted access to roads for two days to allow emergency services to carry out search, rescue and logistics operations more effectively.

Officials have said dozens of people remain unaccounted for. Interior Minister Fernando Grande-Marlaska told radio station Cadena Ser on Friday it was "reasonable" to believe more fatalities would emerge.

But with telephone and transport networks severely damaged, establishing a precise figure is difficult.

Sanchez said electricity had been restored to 94 percent of homes affected by power outages and that around half of the cut telephone lines had been repaired.

Some motorways have reopened but local and regional roads resembled a "Swiss cheese", meaning certain places would probably remain inaccessible by land for weeks, Transport Minister Oscar Puente told El Pais daily.

- 'Overwhelmed' by solidarity -

Thousands of ordinary citizens pushing shopping trolleys and carrying cleaning equipment took to the streets on Friday to help with the recovery.

Susana Camarero, deputy head of the Valencia region, said some municipalities were "overwhelmed" by the solidarity and food they had received.

The movement continued on Saturday as around 1,000 people set off from the Mediterranean coastal city of Valencia towards nearby towns laid waste by the floods, an AFP journalist saw.

Authorities have urged them to stay at home to avoid congestion on the roads that would hamper the work of emergency services.

The storm that sparked the floods on Tuesday formed as cold air moved over the warm waters of the Mediterranean and is common for this time of year.

But scientists warn climate change driven by human activity is increasing the ferocity, length and frequency of such extreme weather events.

© Agence France-Presse