Hopes of finding survivors ebbed four days after torrents of muddy water wrecked towns and infrastructure in the European country's worst such disaster in decades.
Almost all the deaths have been in the Valencia region, where thousands of security and emergency services frantically cleared 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 and civil guards, Sanchez said.
Spain was carrying out its largest deployment of army and security force personnel in peacetime, he added.
Restoring order and distributing aid to destroyed towns and villages -- some of which have been cut off from food, water and power since Tuesday's torrent -- is a priority.
Authorities have come under fire over the 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.
"Thank you to the people who have come to help us, to all of them, because from the authorities, nothing," a furious Estrella Caceres, 66, told AFP in Sedavi.
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.
A video circulating in Spanish media on Saturday showed the head of a civil protection team celebrating the rescue of a person who had been trapped in a car for three days.
With telephone and transport networks severely damaged, establishing a precise figure of missing people 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.
Ordinary citizens carrying food, water and cleaning equipment continued their grassroots initiative to assist the recovery on Saturday.
Around 1,000 set off from the Mediterranean coastal city of Valencia towards nearby towns laid waste by the floods, an AFP journalist saw.
Authorities have urged people to stay at home to avoid congestion on the roads that would hamper the work of emergency services.
Spanish media reported King Felipe VI and Queen Letizia are due to visit the Valencia area on Sunday with Sanchez and regional leader Carlos Mazon.
Mazon called the floods "the worst moment in our history" on Saturday and laid out a series of proposals to help his region recover, ranging from infrastructure to economic support.
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.
Emergency services late Saturday issued an updated of toll of 213 people confirmed killed -- 210 in the Valencia region, two in neighbouring Castilla-La Mancha and one in Andalusia in the south.
Authorities have warned the toll could yet rise however as vehicles trapped in tunnels and underground car parks are cleared.