Rome: Italian President Sergio Mattarella on Monday called for "calm and mutual respect" after Premier Matteo Renzi's defeat in a key reforms referendum plunged the country into political uncertainty.
"Italy is a great country with a lot of positive energy. This is also why we need the political climate to be calm and respectful," Mattarella said in a statement.
A total of 59.11 percent of Italians voted against Renzi's proposed reforms, compared with 40.89 percent in favour in Sunday's referendum on constitutional reforms to overhaul the country's political machinery.
Turnout was relatively high at 65.47 percent in the referendum whose reforms would have given the central government greater powers by reining in the Senate upper house of parliament and Italy's regions.
Mattarella praised the high referendum turnout "as proof of a solid democracy, of a passionate country, capable of active participation" in politics.
The head of state will appoint a caretaker government or to call snap elections after Renzi announced overnight he would resign following the "clear-cut" referendum result.
Renzi is expected to tender his resignation after a cabinet meeting scheduled for 6.30 p.m. local time but Mattarella may ask Renzi to stay on until the parliament passes the 2017 budget bill later this month.
Fresh parliamentary elections are due in Italy in 2018 but the populist anti-establishment Five Star movement and the anti-immigrant Northern League are calling for fresh elections immediately.
"We will start online voting next week on a programme of government followed by a proposed cabinet line-up," Five-Star leader Beppe Grillo wrote on his blog.
"Italians must be called to the ballot-box immediately," he said.
Former Premier and conservative Forza Italia party leader Silvio Berlusconi voted against the proposed constitutional reforms but could form an alliance with the same centre-left majority currently backing Renzi, according to observers.