The Madrid region will extend partial lockdown measures to more areas later this week, officials said, urgently asking for army help with testing and disinfections as virus cases soar.
Wednesday's announcement came two days after the regional government imposed mobility restrictions on 850,000 people in and around the capital -- mostly in densely-populated, low-income districts in the south.
These areas account for 13 percent of the 6.6 million population in the Madrid region -- but 24 percent of virus cases.
Residents cannot leave except for work, school or to seek medical care, but have freedom of movement within the area.
Madrid's deputy health chief Antonio Zapatero told a news conference the restrictions would be extended to more areas which would be identified on Friday.
The regional government was still "studying and analysing" the epidemiological data before making its decision, he added.
Those included in Monday's restrictions have all counted more than 1,000 Covid-19 cases per 100,000 inhabitants -- nearly three times the national average, which in itself is the highest in the European Union.
Local parks have been closed and cafes and restaurants must shut by 10 pm.
Meanwhile, the region's deputy president Ignacio Aguado said his administration would ask the central government for "urgent military logistical support" to "carry out tests and basic disinfection tasks" in the worst-hit areas.
When the pandemic started in March, the army deployed across the country to help with such tasks.
On Tuesday, Health Minister Salvador Illa urged Madrid residents to limit all movements "to the maximum" and restrict social contacts to only the "essential" to reverse a surge in infections.
The Madrid region has recorded 202,600 confirmed cases of the disease and 9,129 deaths -- in both cases a third of the national total.
Since the central government ended a state of emergency on June 21, lifting all national lockdown restrictions, responsibility for public healthcare and managing the pandemic has been left in the hands of Spain's 17 autonomous regions.