ROME (Reuters) - Center-left parties won local ballots in the small Italian regions of Val d'Aosta and Trentino-Alto Adige, results showed on Monday, offering encouragement to Prime Minister Matteo Renzi ahead of bigger regional elections at the end of the month.
Turnout was low and the center-right Forza Italia party of former prime minister Silvio Berlusconi suffered a humiliating collapse, taking only around 4 percent of the vote in Trento, the main town in Trentino-Alto Adige.
But there was a rise in support for the anti-immigrant Northern League party, which has overtaken Forza Italia as the leading party on the right in national opinion polls.
"There's great satisfaction for the excellent result obtained by Democratic Party candidates in the main cities where voting in the local elections took place," Valentina Paris, the official in charge of regional affairs in Renzi's ruling party, said in a statement.
Although local elections have no direct impact on national politics, they are seen as important barometers of popular support for Renzi, who became prime minister without going to the polls last year by ousting his predecessor and Democratic Party rival Enrico Letta.
The local polls in the semi-autonomous regions of Val d'Aosta and Trentino-Alto Adige were held ahead of the main regional elections on May 31.
That poll, in which some 17 million Italians will be eligible to vote in more than 1,000 localities across the country, will be the first major test of electoral support for Renzi since he triumphed in European elections a year ago.
In Aosta, the main town in Val D'Aosta, and in Trento, center-left mayors were elected. In Bolzano, the other main town, the center-left candidate took a strong lead but not enough to secure a win in the first round, meaning a runoff vote will be held on May 24.
(Reporting by James Mackenzie; Editing by Hugh Lawson)