Italian Prime Minister Matteo Renzi has announced his intention to resign after voters rejected his constitutional reform proposals in a referendum held on Sunday 4 December.

In a late-night news conference from the Palazzo Chigi, he said that while he took responsibility for the "extraordinarily clear defeat" in the constitutional referendum, the No camp now has to put forward clear proposals.

"The experience of my government ends here," he said in a televised address. "I have lost and I say it out loud. Good luck to us all," he added.

He plans to convene a cabinet meeting on the afternoon of Monday 5 December and then present his resignation to President Sergio Mattarella.

Mattarella will now be given the responsibility of dealing with the appointment of a new government. If he is unable to do so, he will have to call for early elections.

The state broadcaster RAI has projected that around 40% have voted in support of the reform package, compared with around 60% against. The referendum was over a proposal to streamline parliament, but it many perceived it as an opportunity to register discontent with Renzi's stewardship. Renzi had said that he would resign if he failed to win.

The Interior Ministry has put total voter turnout at 68.33%. Nearly two-thirds of the electorate had voted in prosperous northern Italy, but the voter turnout was lower in the south. Renzi, who took over as prime minister two years ago, had pushed to streamline the country's political system in a bid to push through an economic reform package.

The constitutional reform included cutting down the number of senators and curbing their powers relative to the lower house of parliament. He also sought to reduce the political powers of the regions.

Leaders of the populist 5-Star Movement, the chief rivals of Renzi's Democrats and led by Beppe Grillo, called for early elections. "Today the caste in power lost," said one 5-Star leader, Luigi Di Maio.

"Arrogance lost, from which we'll learn many things in forming our team for government and our platform. Starting tomorrow we'll be working on a government of the 5-Stars, we'll involve the energies and the free persons who want to participate."

Matteo Renzi
Italian Prime Minister Matteo Renzi during a media conference after a referendum on constitutional reform at Chigi palace in Rome, 5 December Reuters