Ten out of 14 districts in Kerala have come under the scanner of various intelligence agencies of the Centre , according to sources in National Investigation Agency (NIA).

The caution by the Centre has come as a follow up to Saturday morning’s arrest in Ernakulam district of three persons with allege link to Al Qaeda. The three were taken to Delhi where they are being questioned about their activities in Kerala.

“Ten districts in the State have sleeper cells of various terrorist organisations and they are under observation. We are also in the process of finding out their associates in the State Police,” said an official who did not want his name to be quoted. The presence of thousands of migrant workers across the State have become a serious issue in Kerala.

An intelligence official said that the Gandhi Bazar in Perumbavoor, a popular shopping centre, is now known as Bhai Bazar because it is frequented by hundreds of migrant labourers.

“But we cannot tell that they are all from Bangladesh. Shops in this centre sell materials brought from their native places like Bengal, Assam and other north eastern States. Some shops even sell paan masala, a product banned in Kerala. But we cannot torment them as they do not create law and order problems on a regular basis,” said the official.

A state police official also said that tough action is initiated against those who violate the tranquillity of the town. “It is difficult to separate grain from chaff. We are proceeding cautiously,” said the inspector tasked with keeping an eye over the migrant workers.