Kannur, Aug 30 (PTI): A Sub-Inspector and two policemen have been placed under suspension after they demanded bribe from three police personnel, including a Superintendent of Police, disguised as workmen of a truck carrying river sand.

The unsuspecting policemen ran into the trap laid by Kannur Superintendent of Police Rahul R Nair, after getting several complaints about them demanding bribes from truckers, especially those carrying river sand in violation of rules, police said today.

The SP and two policemen, the latter in lungi and shabby shirts, got into a truck carrying sand to a construction site in the wee hours yesterday. The truck was carrying sand from Ponnani in Malappuram to Mattannur in Kannur district and it had all required papers.

As the truck entered Kannur district, the SI and policemen from the Control Room at Thalassery stopped it for checking but could not find anything illegal to take up a case.

At this juncture, the SP, who was sitting in the truck's cabin without being noticed told them that the lorry did not have emission certificate, which is liable to attract a fine. The police party then demanded that the trucker pay either Rs 1000 as fine or settle the matter for a mere Rs 100.

The SP then alighted from the truck and revealed his identity to the shock of the three police personnel.He then referred the case to the local Circle Inspector.

The erring policemen were later placed under suspension pending a detailed inquiry, sources said.

Strict rules are in force in Kerala to check river sand mining in view of the threat it poses to the environment.