His government also announced a fresh aid package worth almost 3.8 billion euros as Spain counts the cost of the October 29 disaster that has killed 222 people.

The exceptional Mediterranean storm that lashed the European nation particularly devastated the eastern Valencia region, which has suffered most of the deaths and destruction.

Outrage at the authorities for their perceived mismanagement before and after the floods triggered mass protests on Saturday, the largest in Valencia city which drew 130,000 people.

Demonstrators have demanded the resignation of Sanchez and the Valencia region's conservative leader Carlos Mazon, but the left-wing premier insisted all efforts must focus on reconstruction.

"Later will come the political debate about what things we must improve in the face of this climate emergency," Sanchez told a news conference.

Mazon, who will appear before the regional parliament on Thursday to explain his administration's decisions, conceded that "errors may have been committed" and "everyone" would be obliged to review them.

Critics have questioned the efficiency of the Valencia region's alert system that in some cases only reached residents' telephones after the water began gushing through towns.

Volunteers have supplied desperately needed food, water, medicine and cleaning equipment to some devastated towns as the authorities took days to reach them.

The feeling of neglect has given birth to the slogan "only the people save the people", but Sanchez insisted "we are all the state" on Monday.

- Fresh cash -

The torrents of muddy water wrecked roads and railways, tossed cars, gutted shops and submerged fields, with the final bill expected to soar to tens of billions of euros.

Sanchez unveiled a second aid package worth 3.76 billion euros ($4 billion) to reinforce a cash injection of 10.6 billion euros announced last week.

Compensation will be streamlined and extended to more residents and property, farmers will receive fresh aid totalling 200 million euros and borrowers can benefit from more flexible mortgage repayments until 2026.

Another 500 million euros will go towards clearing mud and debris and repairing swamped sewers in the hardest-hit towns, Sanchez said.

Furlough requests affecting 9,000 people have been submitted and the first insurance claims are being paid out following last week's measures, Sanchez said, adding that the government was shielding the income of around 400,000 workers.

Sanchez has compared the measures to the state's economic intervention during the Covid-19 crisis and said the government "will be there with all the necessary resources and for as long as it takes".

Thousands of soldiers, police officers, civil guards and emergency services are repairing infrastructure, distributing relief and searching for dozens of missing people.

Sanchez said almost all affected homes had been reconnected to the power and telephone networks but repairing roads and railways would take far longer.

National railway company Renfe said the high-speed line connecting Madrid with Valencia would resume on Thursday.

Although Mediterranean storms are common for the time of year, scientists say climate change driven by human activity is increasing the intensity, length and frequency of extreme weather events.