Italy’s former prime minister Silvio Berlusconi, aged 83, is in hospital with early-stage double pneumonia after testing positive for coronavirus, Italian media report.
He spent the night in hospital in Milan for checks, having tested positive on Wednesday.
Earlier his right-wing Forza Italia party said his condition was not a cause for concern, and “he is fine”.
The media tycoon’s partner and two of his children also tested positive.
Berlusconi has been in self-isolation with his 30-year-old partner, the Forza Italia MP Marta Fascina, at his villa in Arcore near Milan, after holidaying in Sardinia.
The infection rate in Sardinia – famous for its Emerald Coast beaches – is higher than in much of Italy.
“A small precautionary hospitalisation was needed to monitor the progress of Covid-19 but he is fine,” said Forza Italia senator Licia Ronzulli.
Berlusconi was transferred to an isolation ward at San Raffaele Hospital on Thursday night. Double pneumonia – inflammation of both lungs – is a common complication with Covid patients. The disease is generally more severe among the elderly and those with other medical conditions.
Berlusconi, a billionaire who used to own AC Milan football team, remains popular in Italy and he has had many messages of support since being diagnosed.
In 2014 he was ordered to do a year of community service after being convicted of tax fraud. His business deals have long been under scrutiny, as have his romantic liaisons, including reports of raunchy “bunga bunga” parties.
Berlusconi addressed party activists in Genoa by phone on Thursday, saying “I’m continuing to work as best I can on the current election campaign”. Separately, he said he did not know how he had caught the virus.
Italy will hold regional elections on 21-22 September, which had to be postponed at the height of the pandemic in Italy in spring.
Last month Berlusconi hosted businessman Flavio Briatore at his luxury Sardinia residence, Villa Certosa.
Mr Briatore, who tested positive for coronavirus in late August, owns a nightclub on the island called Billionaire and used to run the Benetton Formula One racing team.
Mr Berlusconi served as Italian prime minister four times and last year was elected to the European Parliament.
After his conviction for tax fraud he was ejected from the Italian Senate and banned from public office. But later his ban was lifted.