The death toll from the coronavirus in Italy has surged in the past 24 hours by 475 to 2,978 – the biggest single-day jump in any country since the outbreak began.

Officials on Wednesday announced the increase of 19 per cent at the same time as the total number of infections rose to 35,713 from a previous 31,506, up 13.35 per cent.

The Italian government has threatened to ban all outdoor exercise as authorities’ frustration grows over the number of people defying a nationwide lockdown order.

Sports minister Vincenzo Spadafora said: ”If the call to stay at home is not heeded, we will be forced to impose an absolute ban.”

Of confirmed infections in the country, 4,025 patients have fully recovered compared with 2,941 on Tuesday.

Some 2,257 people were in intensive care against a previous 2,060.

Italy, the worst-hit country outside China, 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 has asked recently retired health workers 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 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.

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 Mr Fontana.

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.