Panic has gripped areas along the West Bengal-Bangladesh border as suspected illegal migrants gathered to return to Bangladesh, following a strict anti-infiltration drive by the state's new BJP government.Reports say groups of suspected migrants moved toward the border after the drive intensified. Union Home Minister Amit Shah has called illegal infiltration and unnatural demographic change a serious national challenge and said the Centre is preparing a major action plan.The Border Security Force and state agencies have stepped up checks in border districts. Officials say the drive targets those who entered illegally, but rights groups have raised concerns about harassment of genuine citizens during verification.The development marks one of the most visible consequences of the new state government's hardline posture on infiltration. The Centre's planned action framework is expected to detail verification procedures and penalties.Local administrations in border districts have been asked to cooperate with central agencies while maintaining calm.