On Wednesday his centre-right Forza italia party said that Berlusconi, who will turn 84 at the end of September, had two tests come back positive, but “is continuing to work from his home in Arcore” near Milan, “where he will be spending the planned quarantine period”.
Berlusconi, the scandal-hit politician who once owned AC Milan, stressed that he would continue his political activities.
“I will be present in the electoral campaign with interviews on televisions and in newspapers,” he said during a party video conference.
However he recognised “the limitations imposed on my activities by testing positive for the coronavirus… but I will continue the battle.”
Regional elections are due to take place in two weeks as well as a referendum on reducing the number of Italian parliamentarians.
“He is asymptomatic,” said his doctor, Alberto Zangrillo, according to the daily La Repubblica.
Zangrilio himself was embroiled in controversy in June after claiming that the virus “no longer exists”.
Berlusconi was first tested on August 25 after returning from a holiday in Sardinia where he owns a luxury property.
The result was negative, but he was tested again after some people he met on the Italian island were found to be positive.
These included businessman Flavio Briatore, former managing director of the Benetton Formula One racing team, who was briefly hospitalised in Milan.
Briatore's “Le Billionnaire” nightclub in Sardinia was closed down in August after employees tested positive for the coronavirus.
Berlusconi left for France in late February, at a time when Italy was becoming the epicentre of Covid-19 in Europe.
Forza Italia number two Antonio Tajani said at the time that doctors had warned the political veteran to actively avoid becoming infected.