The city civic authorities have stepped up vigil against encroachment after realising that their laxity had resulted in 400 acres — worth Rs 10,000 crore — being squatted.

The surveillance of civic land has been decentralised up to the borough level as part of the beef-up, which has been prompted by the rising cost of freeing encroached land by relocating the squatters.

In the new system, finalised last week at a meeting between mayor Bikash Ranjan Bhattacharyya and municipal commissioner Alapan Bandyopadhyay, the executive engineer of each of the 15 boroughs will be held responsible for any encroachment of civic land.

“If an executive engineer spots an encroachment, he will have to immediately bring it to the notice of the estate department and the commissioner. The department will take action to remove the squatters from the property,” said Bandyopadhyay.

“Encroachment takes place slowly. In east Calcutta’s Hatgachhia, around 10 acres of civic land are being occupied by more than 2,000 shanties that came up over decades. Had the civic body been more vigilant and acted when the first few shanties sprouted, we could have retained those precious acres,” said Atanu Sarkar, the chief valuer and surveyor of the Calcutta Municipal Corporation (CMC).

The civic body has woken up to the need for increased surveillance after feeling the pinch of rehabilitating squatters. The CMC has recently drawn up a scheme to free around 36 acres of encroached land and rehabilitate the occupiers in housing estates that will take Rs 180 crore to build.

Altogether, 8,980 flats will be constructed on the 36 acres in Garden Reach and East Calcutta under the Jawaharlal Nehru National Urban Renewal Mission.

The project cost — Rs 180 crore — excludes the price of land, which according to the prevailing market rate is Rs 50 crore an acre.

The resettlement scheme is the costliest the civic body has undertaken.