MADRID (REUTERS) - The Madrid region, one of the worst hit by Covid-19 in Spain, is planning to announce restrictions on movement on Friday (Sept 18) that could include targeted lockdowns in virus hotspots, a senior official said, as the country's infections surged again.

Madrid accounts for around one-third of active coronavirus cases in Spain, with a higher incidence in high-density and low-income neighbourhoods, mainly in the south of the capital.

The health ministry registered on Wednesday 4,728 new infections in the past 24 hours, including 1,854 in Madrid. That was up from 3,022 cases reported on Tuesday and brings the cumulative tally to 614,360 - Western Europe's highest. With 17 new deaths, Spain's death toll has reached 30,243.

Madrid also accounts for the highest proportion of hospital capacity occupied by Covid-19 patients, at 22 per cent, way above Spain's average of 8.5 per cent.

"There will be decisions focused on restricting mobility," Antonio Zapatero, head of the Covid-19 response for the region, told reporters, adding the health department was considering locking down areas with the highest incidence of the virus.

"There has been a relaxation of behaviour that we cannot afford," he said, adding people were organising parties, drinking in the street and not respecting quarantine rules.

Since restrictions on movement were lifted and mass testing began in late June, infections have risen in Spain from a few hundred a day to thousands. Deaths have also increased to 50-60 per day in the past two weeks from single digits in July.

"Many people are doing whatever they feel like, so I do think we need to have more measures," said Ines Diaz, a Madrid resident.

The latest plan comes amid controversy in Spain over who is to blame for the increase in infections, with regions and the central government pointing fingers at each other.

Adding to the tensions, Madrid's regional chief Isabel Diaz Ayuso said earlier this week "the way of life of immigrants" was partly to blame for the surge, attracting huge criticism.

"We condemn your words that promote a racist stigma on our communities", non-profit association SOS Racismo Madrid said on Twitter, adding that migrants usually have more precarious jobs, underprivileged housing and are more exposed to the virus.

Also controversial is the region's estimate, which it included in a report published on Tuesday, that around 40 per cent of the active infections concern "people born outside Spain".