The Vatican has yet to release details of the guest list, beyond saying that it will include delegations from Italy and Benedict's native Germany.
Italian Prime Minister Giorgia Meloni, who at the weekend joined world leaders from Joe Biden to Vladimir Putin in paying tribute to Benedict, was among the first to visit his body on Monday morning.
She was greeted by Archbishop Georg Gaenswein, Benedict's long-time aide.
Faithful servant
The last papal funeral, of John Paul II in 2005, drew a million faithful and heads of state from around the world, although Benedict was a more divisive figure.
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A brilliant theologian, he alienated many Catholics with his staunch defense of traditional values and as pope struggled to impose his authority on the church as it battled a string of crises, including over clerical sex abuse.
His successor cuts a very different figure, an Argentine Jesuit who is most at home among his flock and has sought to forge a more compassionate church.
Pope Francis paid tribute to Benedict in three New Year's events at the Vatican over the weekend, "thanking God for the gift of this faithful servant of the Gospel and of the Church".
Francis, 86, has raised the prospect that he might follow Benedict's example and step down if he became unable to carry out his duties.
In July, suffering knee problems that have forced him to rely on a wheelchair, he admitted he needed to slow down or think about stepping aside.
Last month, Francis revealed he had signed a resignation letter when he took office should poor health prevent him from carrying out his duties.
Source: Agence France-Presse
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