Italian anti-establishment candidate Virginia Raggi took the lead in the first round of the Rome mayoral race Sunday and will face the ruling party's contender in a run-off vote, exit polls showed.

Raggi, of the populist Five Star party, won between 33 and 38 percent of votes, according to exit polls by public broadcaster RAI and La7 television.

She was trailed by Robert Giachetti of Prime Minister Matteo Renzi's centre-left Democratic Party (PD), who secured 20 to 26 percent of the vote.

A second round is expected to take place on June 19.

Rome has been without an elected leader since last October, when Ignazio Marino, a member of PD, was forced to quit over an expenses scandal.

The municipal elections that took place in Rome and other Italian cities Sunday are widely seen as a test for Renzi's party and the country's divided right.

Losing control of Rome would not augur well for Renzi four months before a referendum on constitutional reforms designed to end decades of gridlock in parliament.

Renzi has vowed to resign if voters reject the reforms.

Five Star is hoping that success in Rome will give it the platform it needs to transform itself into Italy's main opposition in the run-up to national elections due by June 2018 at the latest.

Nationwide, more than 13 million people were eligible Sunday to choose members of 1,300 municipal councils in a two-round ballot.