At least 631 people have now died from coronavirus in Italy – an increase of 168 in a single day.
The 36% rise is the biggest since the COVID-19 contagion first came to light there on 21 February.
Almost a thousand extra cases of coronavirus were recorded in 24 hours – reaching 10,149.
The head of the country’s civil protection agency said 877 people were in intensive care – up from 733 on Monday.
Just over 1,000 have now fully recovered.
Italy already had Europe’s worst outbreak and experts are warning that the peak of the spread may not arrive until mid-April in the north – so far the country’s hardest hit area – and possibly later in other regions.
“Citizens must know that this is not about changing their lifestyle just for one or two weeks,” said the head of the national centre for epidemiology, Stefania Salmaso.
Restrictions “will likely have to be kept for a long time”, she told the ANSA news agency.
Mario Monfreda, who runs a restaurant in the capital, said it “looks like an apocalypse has struck – there is no one around”.
Globally, there are more than 116,000 confirmed cases, and over 4,000 deaths, according to figures collated by Johns Hopkins University in Baltimore.
British Airways and Ryanair are to suspend all flights to and from Italy after the entire nation was placed in lockdown.
An easyJet spokesman said on Tuesday evening that it was in the “process of cancelling all of its existing scheduled flights touching Italy between 10 March and 3 April”, adding that it would be “operating some rescue flights in the coming days”.
The Foreign Office has warned Britons against all but essential travel to the whole of Italy. People arriving in the UK from anywhere in the country have been told to self-isolate for 14 days – even if they do not have symptoms.
Portugal has suspended all passenger flights to and from Italy from Wednesday for 14 days.
Austria is to introduce border checks and deny entry to people arriving from its neighbour, Chancellor Sebastian Kurz has said.
He added that those with a doctor’s note, certifying they were healthy, would be treated as an exception.
New measures announced in Italy late on Monday clamp down on movement and close down public spaces. They widen steps already taken in the rich northern region of Lombardy and parts of neighbouring provinces.
All public gatherings are banned, sports events including football matches are suspended, and movement is being severely restricted across the nation in an attempt to contain COVID-19 – the disease caused by coronavirus.
Schools and universities will be closed until at least 3 April, and ski resorts are shut.
The new measures amount to the biggest restrictions of movement for 60 million Italians since the Second World War.
People can only move around for work, health needs or emergencies. Anyone travelling will have to fill in a document declaring their reasons and carry it with them.