Citizens are turning out in 790 towns and cities including 13 provincial capitals: Ancona, Brescia, Brindisi, Imperia, Latina, Massa, Pisa, Siena, Sondrio, Teramo, Terni, Treviso and Vicenza.

Italian dailies have identified five key battlegrounds: Brescia, Ancona, Vicenza, Pisa and Siena, the first two of which are currently governed by the centre left and the last three overseen by the centre right.

The possible second round of voting in towns with more than 15,000 inhabitants where the mayoral candidate has not obtained 50 per cent +1 of the vote will take place on May 28-29.

Trentino and Val d'Aosta will vote on May 21 and Sicily and Sardinia on May 28-29, so their possible run-offs will follow later.

Voting stations opened at 7am on Sunday and will stay open till 11pm on Sunday night, before reopening from 7am to 3pm on Monday.

ANSA