ROME (Reuters) - The Italian government threatened on Wednesday to ban all outdoor exercise as the coronavirus death toll soared to 2,978 and frustration grew over the number of people defying a nationwide lockdown order.

Italy was the first Western country to impose severe restrictions on movement to contain the illness. But a week after the curbs were imposed, the disease is still spreading and hospitals in the north are at breaking point.

The northern region of Lombardy, on the frontline of the battle against the respiratory pandemic, asked recently retired health workers on Wednesday to return to work and help colleagues overwhelmed by the crisis.

“I make a heartfelt appeal to all the doctors, nurses and medical personnel who have retired in the last two years...to help us in this emergency,” regional Governor Attilio Fontana told a news conference.

The national death toll surged by 475 over the past 24 hours, the largest increase in numerical terms since the outbreak first came to light on Feb. 21. The total number of confirmed cases grew by 4,207 to 35,713.

“I believe that in the coming hours we will have to consider the possibility of a complete ban on outdoor activities,” Sports Minister Vincenzo Spadafora told state broadcaster RAI.

The government lockdown banned all non-essential travel, but allowed people to take solitary daily exercise, if needed. Looking to enforce the restrictions, police have stopped more than one million people over the past week and booked almost 43,000 for violating the rules, the interior ministry said.

“If the call to stay at home is not heeded, we will be forced to impose an absolute ban,” he said.

The real number of deaths could be much higher than the official figure, after it emerged that fatalities in nursing homes - where dozens of patients are dying each day - are not being registered as coronavirus-related because none of the sick are being tested.

“There are significant numbers of people who have died but whose death hasn’t been attributed to the coronavirus because...they weren’t swabbed,” said Giorgio Gori, mayor of the town of Bergamo, one of the worst hit areas.

MEDICAL WORKERS

While many Italian cities have been largely empty over the past week, photographs have circulated on social media of public transport filling up in the financial capital Milan, suggesting that some people are going back to work.

“Every time you leave your home, you are putting yourself and others at risk,” said Fontana.

A person is jogging near Tiber river, as the spread of the coronavirus disease (COVID-19) continues, in Rome, Italy March 18, 2020. REUTERS/Yara Nardi

Lombardy, like many regions, is rushing to build makeshift hospitals to add badly needed intensive-care units. However, the move is being complicated by the fact that doctors, nurses and hospital porters are themselves falling sick. Some have died.

The Gimbe Foundation research group, using data supplied by the national health authority, said that between March 11-17, some 2,529 health workers had been diagnosed with coronavirus - 8.3% of the national total of coronavirus cases.

Officials warned that if the incidence of new cases did not slow in the coming days, they might extend the lockdown already in place, both in terms of the types of restrictions and how long they will continue.

In successive decrees earlier this month, the government ordered restaurants, bars and most shops to close until March 25. In addition, it shut schools and universities and told everyone to stay home unless absolutely essential until April 3.

Since the restrictions were most recently ramped up on March 12, the number of deaths has more than tripled.

“I do not know if the measures will be extended beyond April 3. We will make a decision based on the numbers and events. I cannot rule it out. We will see in the coming days,” said Infrastructure Minister Paola De Micheli.