Milan, July 17 - A migrant from Guinea was arrested after trying to stab a policeman near Milan's central rail station Monday. The officer, who was protected by his bullet-proof vest, sustained a slight wound, sources said. The man had been reported for trying to get on a tourist coach armed with a knife, they said. The aggressor, who is being tested to see if he had taken drugs, was named as 31-year-old Saidou Mamoud Diallo. He had been served an order of expulsion from Italy, issued in Sondrio on July 4. He also had a record of violence, threats and resisting arrest. The incident spurred anti-immigrant Northern League MP Paolo Grimoldi to call for "mass expulsions" of migrants. "Is (Interior Minister Marco) Minniti going to wake up or is he going to wait for a dead body?" he asked. Milan Mayor Giuseppe Sala said "controls are the only answer to these problems".