Vigil has been stepped up along the Kerala coast following a warning by the Centre about the possibility of extremist forces infiltrating through the sea for carrying out subversive activities, state Home Minister Kodiyeri Balakrishnan informed the Assembly on Tuesday.

Besides stepping up coastal patrolling, the authorities concerned have been instructed to review the security of strategic spots, he said.

An internal security monitoring system has been put in place under an inspector general of police and special cells set up in each district. Coordination among the police and intelligence agencies has also been increased.

The Centre has also given permission to set up coastal police stations.

He, however, said the government had not received any report on the possibility of Hindu and Muslim extremist outfits making plans to unleash communal clashes in the state.