Spain's cabinet was to open urgent talks on Friday to consider imposing a state of emergency in Madrid after judges overturned a partial lockdown that was opposed by the regional authorities.

Thursday's bombshell court decision in effect cancelled restrictions covering some 4.5 million people in and around the capital, where the rate of infections is twice the national average.

Caught in a bitter standoff with Madrid's rightwing administration which opposes the restrictions, Spain's socialist Prime Minister Pedro Sanchez has issued an ultimatum: either the region passes the measures itself, or the government declares a state of emergency to push them through.

Imposed on October 2, the restrictions barred residents of the capital and nine nearby towns from leaving the city limits except for work, school or on medical grounds, and also imposed an 11:00 pm curfew on bars and restaurants.

Ahead of the cabinet meeting, Madrid government leader Isabel Diaz Ayuso, a member of the conservative Popular Party, was locked in talks with her administration to decide what to do. In a phone conversation late on Thursday, Sanchez told her the region could issue an order validating the restrictions or ask the central government to impose a state of emergency to ratify the measures.

The third option was for the central government to impose such a measure, he told her, saying that in all three cases, the restrictions would remain the same.

With Sanchez away at a ceremony in Barcelona with King Felipe VI, the cabinet meeting was to be chaired by Carmen Calvo, one of his deputies.

"We have been continually reaching out to the region to deal with the situation to ensure that these measures are kept in place in order to contain the pandemic in Madrid," Calvo said ahead of the meeting.

"We have only one objective: to protect Madrid.. If the community cannot do it, we will."

Call for responsibility

Despite opposing the partial lockdown of the capital, mainly on economic grounds, Diaz Ayuso urged residents to stay within city limits, especially over the forthcoming three-day weekend for Spain's National Day on October 12.

"We remain in a situation where incidence of the virus remains very, very high," national emergencies coordinator Fernando Simon warned on Thursday, urging people to act responsibly.

"If people go to their second residence in the mountains, or go on holiday even within the region, it implies risk."

Meanwhile, a group of scientific and medical organisations representing 170,000 professionals published a letter online pleading for an end to the political infighting.

"You must accept, once and for all, that to deal with the pandemic, key decisions must be based on the best-available scientific evidence and completely disconnected from the ongoing political confrontation," it said.

By late morning the petition, which was published on change.org, had been signed by nearly 100,000 people.

The court refused to ratify the restrictions on grounds they were imposed by the central government and not by the regional authorities.

The infection rate in the region of Madrid currently stands at 564 cases per 100,000 people, compared with just 257 in the rest of Spain, which is the highest in the European Union.