"We have stopped the drinking water supply and are making scientific tests to verify reports of poisoning at East Nayar river," UJS Secretary Appraisal P C Kimothi said here.
Villagers staying close to the river have alleged that some miscreants had poisoned the water leading to the death of hundreds of fish. Two dogs were also found dead on the river bank.
The poisoned area is near the source of water supply to 17 villages in the region, Kimothi said.
The allegations have come at a time when the region is reeling under an intense hot spell, leading to water scarcity.
The area's District Forest Officer M B Singh said he had asked the Range officers of Pokhara and Thailisain forest Range, near the river, to investigate the matter and report to him immediately.
SDM Thailisain, Madan Ram, also directed officials to investigate the matter and file a report.