Italy's former prime minister Silvio Berlusconi is being treated for a type of chronic leukaemia, hospital doctors in Milan have confirmed.
He was rushed to intensive care on Wednesday with breathing problems and doctors said he was suffering from a related lung infection.
A four-time prime minister and media mogul, Mr Berlusconi, 86, still leads his party and is an elected senator.
But he has had repeated health problems since he contracted Covid-19 in 2020.
Colleagues have expressed hope that he will still be able to return to front-line politics as he continues to lead Forza Italia, a centre-right junior partner in Prime Minister Giorgia Meloni's coalition.
"We want to be optimistic," said Antonio Tajani, Italy's foreign minister and one of the most senior figures in Mr Berlusconi's Forza Italia party.
Mr Berlusconi has combined politics with a business career at the helm of a media empire. He last served as prime minister in 2011, although his latter years in power became overshadowed by sex and corruption scandals.
He was elected to Italy's upper house, the Senate, last September but has repeatedly required hospital treatment. He returned to hospital in Milan on Wednesday only six days after he was discharged following days of check-ups.
His personal doctor, Alberto Zangrillo, said his lung infection was related to a chronic blood condition that he had borne for some time. Earlier reports said he had begun chemotherapy to fight the leukaemia.
"He's stable. He's a rock. he's going to make this time too." said his younger brother Paolo Berlusconi earlier.
His return to hospital has caused concern in Italy and politicians from across the spectrum have wished him well. Ms Meloni has wished him a speedy recovery, tweeting the words "Forza Silvio" - "Come on Silvio!", echoing the name of his political party.
His fiancée Marta Fascina, who is an MP in his party, spent the night with him in the hospital and his children visited him on Thursday for a second time.
Forza Italia officials said their leader had spoken on Thursday morning to party figures including Mr Tajani and Maurizio Gasparri, vice president of the Senate.
Mr Berlusconi remains a divisive figure in Italian politics. Earlier this year, he was finally cleared of bribing young showgirls to lie about his notoriously raunchy "bunga bunga" parties.
However, both left-leaning and right-leaning newspapers have paid tribute to the charismatic, yet controversial, politician and media tycoon.
Several newspapers have wished him well, while others have highlighted the potential impact of his illness on the country's political landscape.
"Everyone with Silvio" was the main headline in Il Giornale, which belongs to the Berlusconi family, expressing its support and solidarity.
Like the prime minister, Libero, another right-leaning newspaper, opted for "Forza Silvio", while La Repubblica called him the "fearless Knight". The centre-left daily has for decades strongly criticised his political actions and extensively covered the repeated scandals surrounding Mr Berlusconi.
Although his entourage has downplayed the seriousness of his condition, his illness has raised questions about the future of his political party.
Forza Italia may be part of the ruling coalition but it has been in decline in recent years, and Mr Berlusconi's declining health may further weaken its position. When Mr Tajani spoke to reporters, he said there was only one party leader: "Now let's hope he returns to lead the party."
His condition has also revived questions about the future of the Berlusconi business empire, which includes several television channels and publishing companies, making him one of the most influential media moguls in Italy.
His family also owns a minority stake in football club AC Monza, which has climbed from the third tier of Italian football to Serie A during his five-year ownership.
"Warm wishes, dear president, from the whole big red-and-white family," tweeted club president Adriano Galliani.
