Giuseppe Conte told an Italian newspaper it looked likely that the set end date, 3 April, would be pushed back.
“At the moment it is not sensible to say anything else,” he told Il Corriere della Sera, “but it is obvious the measures we have taken - whether that be shutting down much of the country’s individual and business activities, or our actions regarding schools – can only be extended.”
Italy has been in lockdown since 10 March as authorities work to combat the spread of Covid-19 in the second worst-hit country in the world after China, where the virus originated.
All of Italy on lockdown as Coronavirus spreads
“We have avoided the collapse of the system,” Mr Conte said. ”Restrictive measures work.”
The PM said told the newspaper he hoped infection rates would start to go down in the next couple of days, but warned Italy “could not go back to how life was before straight away”.
Under current measures, Italy's 60 million people are only allowed to travel for work, medical reasons or emergencies under an order that runs until 3 April.
Meanwhile most shops, except those selling food and pharmacies, have to told to remain shut until 25 March.
However, both deadlines could be pushed back as the country continues to battle its Covid-19 outbreak, Mr Conte has suggested.
More than 35,700 people have been infected with coronavirus - a flu-like disease that can develop into pneumonia - in Italy, according to figures on Thursday.
Nearly 3,000 people diagnosed with Covid-19 have died in the country to date, while around 4,000 have recovered.
Additional reporting by Reuters