This was the second big cat death reported in the wildlife sanctuary within a fortnight.
The villagers saw the carcass of the tiger under Dhevra bridge and informed the forest department about it yesterday, divisional forest officer Gyan Prakash Singh said.
A team led by field director of Dudhwa Tiger Reserve Sunil Chaudhary and WWF went to the spot and sent the carcass to Indian Veterinary Research Institute (IVRI) in Bareilly for post-mortem, the DFO said.
He said the carcass was that of a male tiger about two- years-old and the cause of death will be known only after getting a report from the IVRI.
According to the last census, there are around 24 tigers in Katarniaghat Wildlife Sanctuary and all efforts are being made to provide security to wildlife, Singh said.