(ANSA) - Milan, October 10 - Domenico Zambetti, an executive councillor in the Lombardy regional government, was arrested on Wednesday for allegedly buying votes from the 'ndrangheta mafia syndicate. Zambetti, a member of ex-premier Silvio Berlusconi's People of Freedom (PdL) party, is accused of paying two mobsters 200,000 euros for 4,000 votes (at 50 euros each) in the 2010 elections for the assembly of region around Italy's business capital Milan. His arrest takes the number of councillors in the Lombardy regional executive and assembly who are under investigation up to 13. They include Governor Roberto Formigoni of the PdL who is accused of corruption related to health contracts. Wednesday's development is the latest in a string of corruption scandals that have hit various parts of Italy's political spectrum in recent months. The PdL was already in turmoil over the case of its former caucus chief in Lazio, Franco Fiorito, who was arrested last week on suspicion of embezzling public money. That caused caused Renata Poverini to resign as governor of Lazio last month. Experts say the scandals have strengthened widespread public disaffection with the nation's political class and contributed to the rise of comedian Beppe Grillo's grassroots Five Star movement, which is opposed to the present party system. The Five Star movement is vying with the PdL for second place in the polls, according to several recent surveys. The 'ndrangheta is a powerful Calabria-based organized crime syndicate that has laid down roots in other parts of Italy, especially wealthier northern regions, in recent years.