Kolkata, Nov 30 (ANI): BJP President Amit Shah on Sunday while addressing a rally in Kolkata said that aid the Trinamool government is obstructing the NIA probe because of the involvement of the party leaders in the Burdwan Blast case. Accusing Kolkata Chief Minister Mamata Banerjee for sheltering the Bangladeshi immigrants, Shah said that Mamata Banerjee may continue doing vote bank politics but should not risk country's security.