The presidential office said on Monday that Mattarella had asked outgoing prime minister Matteo Renzi to stay in place until the government had passed its 2017 budget.

The Italian premier had been at the Quirinale Palace, the presidential residence, to formally offer his resignation to Mattarella.

"The prime minister, following the outcome of the constitutional referendum held yesterday, announced that he could not continue with the mandate of the government and has therefore expressed his intention to resign," a statement said.

"The president of the republic, given the need to complete the parliamentary process of approval of the budget law... asked the prime minister to postpone his resignation until this requirement has been fulfilled."

It remained unclear whether Renzi had accepted the task.

Renzi had said he would resign after voters in a referendum squarely rejected his plan for constitutional reform. However, Mattarella urged him to put his planned resignation on hold until parliament had approved the 2017 budget. It was expected that could be done as early as Friday.

Of those who voted for Renzi's plan for constitutional reform - which would have seen the size and power of the Senate limited and which would have centralized power away from the regions - some 60 percent were against. The result sent shockwaves around Europe, being seen by many as a vote against reform and in favor of a populist and more anti-EU agenda. Markets were initially spooked, but appeared to recover.

rc/se (dpa, AP, AFP)