(ANSA) - Naples, March 8 - Demonstrators and police clashed outside the offices of Naples newspaper Il Mattino Wednesday while anti-immigrant, anti-euro Northern League leader Matteo Salvini was inside addressing a forum. The protesters shouted slogans against the formerly secessionist leader, who has turned his party into a nationwide one but still regularly gets barracked in southern Italy. "I'm ready to challenge (ex-premier and likely future premiership candidate Matteo) Renzi (of the ruling centre-left Democratic Party) and govern Italy better from tomorrow," Salvini told the forum. Addressing the vexed question of who should lead the centre right in the next elections, now expected early next year, he said: "All the best to (ex-premier and centre-right Forza Italia leader Silvio) Berlusconi but it's the voters who should decide who gets to be leader. "On what basis should Berlusconi get to be leader?" He issued a message for Neapolitans: "Let's get to know one another, let's learn to respect each other". The demonstrators were from leftist and anarchist squats known as 'social centres' in Italy.