The two, who are inhabitants of Jaigaon in Bhutan border, were apprehended from a dhaba at Odlabari area last night during a raid, they said.
The leopard skin was being smuggled to Siliguri from Assam via Bhutan and was to be sold in Nepal, the officers said.
Guessing from the marks in the leopard skin, they felt that the animal was shot dead.
The two confessed that the leopard skin was to be sold for Rs 9 lakh, they added.