Spain reported a record 93,822 new coronavirus infections over the weekend, while the two-week average jumped to a new high of 885 cases per 100,000 people on Monday as regional authorities scrambled to ramp up restrictions.
Infections now total 2,593,382, while the death toll increased by 767 to 56,208, health ministry data showed.
"Spain is not doing well and we have to be aware of it," Health Emergency Coordinator Fernando Simon told a news briefing.
Simon stressed that further measures would be needed for transmission to fall quickly and ease pressure on intensive care units after weeks of gradual tightening have failed to tame a rampant third wave.
He said the highly contagious variant of the virus first detected in Britain was not responsible for the surge and only accounted for around 5% of current infections, although it could become the dominant variant by March.
With Spain's 14-day incidence of the virus more than tripling from a month ago, regions have raced to curb infections - although national law bars them from imposing the harshest restrictions like home confinement.
Health Minister Salvador Illa, meanwhile confirmed he would step aside to run for election in Catalonia after leading Spain's response to the pandemic.
Regional Policy Minister Carolina Darias, who has worked closely with Illa, is most likely to step in, a source close to the government said. Illa's replacement will be announced on Tuesday, the prime minister's office said.
The regions brought in a range of restrictions. Galicia imposed limited people to socialising only with members of their own household and ordered non-essential businesses to close at 18.00 for three weeks.
Regional leader Alberto Nunez Feijoo urged citizens to stay at home from 20.00
Valencia and Murcia banned gatherings of more than two people. Madrid will bring forward a curfew by an hour to 22.00 and deploy drones and extra police to ensure compliance.
"It's terrible because things were getting better, people were going out, but this is creating fear again," said Baldomore Curas, manager of a bar in central Madrid.