Why is West Bengal opposed to increased BSF jurisdiction?

Darjeeling: The amendment of the BSF Act increasing the jurisdiction of the Border Security Force (BSF) from 15 to 50 km from the international borders of Bangladesh and Pakistan, has invited flak from different quarters. Dubbing it as a politically motivated move by the BJP-led Union Government, many feel that it is an attempt to dilute the federal polity and exercise a tighter grip on the opposition-ruled states. 

The BJP declared that the move is to counter illegal infiltration that has triggered demographic change along with preventing trans-border crime. The BSF, too, has reiterated the same, adding that the change in demography in some border districts has led to a change in voting pattern.

Punjab and West Bengal have moved resolutions in their state assemblies urging the Union Government to immediately roll back the new law that has been implemented unilaterally, without consulting state governments. West Bengal Chief Minister has met Prime Minister Modi and requested a rollback.