Pope Francis on Saturday paid tribute to his "dearest" predecessor Benedict XVI, who died earlier in the day aged 95.

"With emotion we remember a person so noble, so kind," Francis said at a New Year's Eve service in St Peter's Basilica, offering thanks "for all the good he has done" and underlining "his sacrifices offered for the good of the church".

Bells tolled in Rome as news of Benedict's death, which followed a rapid decline in his health over Christmas, spread to the faithful on an unusually warm winter's day. Many went to pray in St. Peter's Square on hearing the news.

"Now we will only have one pope. I must say that Pope Ratzinger was a charismatic pope, humble but above all a great theologian," said French tourist Emilie Gaillard, using Benedict's family name.

The Vatican said his body would lie in state from Monday in St. Peter's Basilica and that Pope Francis will preside at his funeral on Thursday morning in the same square where Benedict, who was then Cardinal Joseph Ratzinger, said the funeral Mass for his predecessor, Pope John Paul II, in 2005.

The Vatican has painstakingly elaborate rituals for what happens after a reigning pope dies but no publicly known ones for a former pope - one of the many complications created by Benedict's resignation.

The Vatican said official government delegations at the funeral would be limited to those from Germany and Italy. Other dignitaries could attend in a private capacity.

Leaders were swift in sending their condolences for Benedict, who was the first German pope in 1,000 years.

"We mourn the death of our Bavarian Pope," said Markus Soeder, premier of Benedict's home state. German Chancellor Olaf Scholz said on Twitter that the world had lost "a formative figure of the Catholic Church".

Italian Prime Minister Giorgia Meloni hailed Benedict as "a great man who history will not forget", while Polish President Andrzej Duda called him "one of the greatest theologians of the 20th and 21st centuries".

French President Emmanuel Macron said Benedict had "worked with all his soul and intelligence for a more fraternal world".

Britain's King Charles said he remembered his meeting with Benedict with fondness and noted "his constant efforts to promote peace and goodwill to all people, and to strengthen the relationship between the global Anglican Communion and the Roman Catholic Church." (AFP/Reuters)