The exceptional Mediterranean storm that lashed eastern Spain a week ago triggered surging torrents of muddy water that have left a trail of destruction and an unknown number of missing.

Prime Minister Pedro Sanchez announced a series of measures including aid to small and medium-sized businesses, self-employed workers and households who have suffered deaths, incapacity and damage to homes and belongings.

Tax relief and a three-month postponement to repaying mortgages and loans were also among the announcements, which Sanchez likened to the state's intervention during the Covid-19 pandemic to protect the economy and livelihoods.

The government would take on all emergency spending by local councils linked to clearing mud, debris and ruined property and restoring drinking water, Sanchez said.

Spain has also requested aid from the EU solidarity fund, he added.

Security force and emergency services personnel are working around the clock to repair damaged infrastructure, distribute aid and search for bodies in Spain's largest peacetime deployment of its armed forces.

Sanchez said almost 15,000 troops, police officers and civil guards were in the eastern Valencia region which has suffered most of the deaths and destruction, up from 7,300 on Saturday.

Firefighters combed through piles of damaged vehicles and pumped out water from inundated garages and car parks where more victims may be discovered, AFP journalists saw.

Maribel Albalat, mayor of the ground-zero town of Paiporta, told public broadcaster TVE they were doing "better, but not well" with many streets still inaccessible and residents struggling to get a phone signal.

Rescuers in the southeastern town of Letur have found one of the missing bodies they were looking for, announced the central government's representative in the Castilla-La Mancha region, Pedro Antonio Ruiz.

- 'Only the people are helping' -

Many survivors are furious with the authorities for failing to warn the population on time last Tuesday and provide urgent rescue and relief work.

That anger reached breaking point in Paiporta on Sunday when crowds heckled and hurled mud at King Felipe VI, Queen Letizia and Sanchez.

"Only the people are helping... And the politicians, where are they? Why didn't they raise the alarm? Murderers!" Matilde Gregori, 57, told AFP in the mud-soaked town of Sedavi.

"They don't know how to take care of their people, let them go home... We know how to do better," said Gregori, whose shop fell victim to the floods.

The authorities have warned survivors to shield themselves from health hazards in the stagnant flood water, which may contain toxic waste, chemicals or bacteria from dead humans and animals.

Biology teacher Jose, 58, wore a mask and gloves during the clean-up of a garage in Sedavi awash with water for almost a week.

"Having stagnant water that can breed germs is a great danger that we want to avoid... We'll see if we can manage," he told AFP.

Storms coming off the Mediterranean are common during this season. But scientists have warned human-induced climate change is increasing the ferocity, length and frequency of extreme weather events.

"Climate change kills... we have to adapt to this reality," Sanchez said in his news conference, lashing out at the "irresponsible discourse of deniers".