Over 3,500 ducks owned by a poultry farmer have died in a nearby village after consuming suspected polluted water on the Palar riverbed and tests have also ruled out any outbreak of disease for the en masse deaths of the birds, a top official said in Vellore on Friday.

Gopinath, a poultry farmer, had been rearing 3,500 ducks at nearby Periya Komeswaram village. The birds were found dead in bunches on June 13 and 14.

"The ducks had drunk water stagnant on some stretches of the Palar riverbed. We suspect the water might have been heavily contaminated and toxic," said a top district animal husbandry official, who did not wish to be named.

He said tests carried out to ascertain if the ducks had died of any disease outbreak had confirmed that it was not so.

"Test result today confirmed that the deaths are not due to any disease outbreak. It was not due to any disease that affects birds (including ducks)," he told PTI.

"The poultry farmer has 1,000 more ducks and these are reared in a separate enclosure by him. These birds are confined to the enclosure and have not been affected." 

He said only those ducks that drank water from the riverbed had died.

To a question, he said "such deaths happen when the level of toxicity in the water goes beyond a particular level." 

He said an FIR has been registered and a forensic test would be done to determine the cause of ducks' deaths.

Water samples from the riverbed and vital organs of the dead ducks are being sent for forensic test, he said.

Veterinary authorities are also seized of the matter and they are looking into it, he said.

The deaths occurred close to nearby Ambur town, which houses many tanneries.

There have been charges from environmentalists that the Palar river and the riverbed areas have been polluted due to discharge of effluents let out by tanneries.