Calcutta, Nov. 10: A multi-pronged operation — on water and from air — has been launched to trace several fishing trawlers, suspected to be from Thailand, which allegedly opened fire on fishermen on Indian waters on Saturday.

Sundarbans development minister Kanti Ganguly said fishermen living in villages of Raidighi and Kakdwip had complained against these trawlers yesterday.

“They (the Indian fishermen) have lodged complaints with the police, saying those on the Thai trawlers opened fire on them. Law-enforcing agencies have taken the matter seriously and are still engaged in the search,” he said.

South 24-Parganas police officials said the firing started on Saturday when Indian fishermen, on seeing alien trawlers poaching, asked them to stop.

The face-off occurred on Bhangaduni river near Kendo island, close to the Indo-Bangladesh border, where the foreign trawlers — described as equipped with “very sophisticated” machinery that could damage the marine ecological system — were first spotted, the officials added.

The administration swung into action immediately, launching a multi-agency operation from air and on the surface. The district police teamed up with the Coast Guard and the Border Security Force on Saturday to spot the intruders.

A hovercraft left shore at Shamsherganj in East Midnapore and sped towards the area where the intruders were spotted by Indian fishermen. Another hovercraft was kept ready for any emergency. Today, a Dornier aircraft left the coast guard base at Haldia, Coast Guard commander in Haldia B. Rajputran said.

Both the hovercraft and the aircraft, however, touched base without any success, officials said. Another Dornier will be pressed into service as the dense forests made the job difficult for spotters on the surface.

“There have been definite reports of intrusion by unauthorised people of a foreign country in highly-sophisticated fishing trawlers,” district magistrate Alapan Bandyopadhyay said. “They have not yet been traced and neither have we been able to establish their identity,” he added, advising caution on labelling the intruders as Thais.

The trawlers might have strayed into Indian waters, officials said, but the behaviour of the crew was a cause for worry. This is not the fishermen’s and the law-enforcing agencies’ first brush with alien trawlers, mostly from Thailand, they added.