MILAN — Premier Mario Monti of Italy criticized his predecessor, Silvio Berlusconi, Thursday for demonstrating ‘‘a certain volatility in judgment’’ and urged the center-left leader to jettison extremists who he said will make the country’s path of reform more difficult.

Monti has changed tone in recent days, dropping his neutral technocratic stance as he seeks a second term, this time at the helm of a coalition of centrist parties in February elections. He is now directly challenging leaders who until a few weeks ago backed his nonelected government.