(ANSA) - Milan, December 18 - Alleged members of the Calabria-based 'Ndrangheta crime syndicate were arrested early on Wednesday on extortion charges aggravated by mafia-style intimidation in the northern Lombardy region and in a number of southern cities, Carabinieri police said. Anti-mafia prosecutors in Milan issued the arrest warrants. Police carried out an unspecified number of arrests and extensive searches as part of a probe into mafia-linked businesses in Lombardy which led on October 2012 to 23 arrests of suspected members of 'Ndrangheta's powerful Mancuso clan with business interests in Milan. Italy's major mafia organizations are all based in the south. In recent years however syndicates like 'Ndrangheta and the Naples-based Camorra have made major inroads in the richer industrial north.