The census of the Amur leopards was conducted in Russia's Primorsky Krai region, China's state-run Xinhua news agency reported Wednesday.
The Amur leopard, also known as the Far Eastern leopard, Korean leopard and Manchurian leopard, has been classified as critically endangered since 1996 by the International Union for Conservation of Nature.
Only 14 to 20 adults and five to six cubs were counted in a census in 2007.
Experts studied the traces of the wild cats in the National Park Land of the Leopard and Kedrovaya Pad Nature Reserve but said it would take time to establish the exact number of the leopards in the Russian territory.
A second count, scheduled from late January to early February, will count leopards in two protected areas of China along the Russian border, experts said.
China and Russia are cooperating in protecting the leopards because the animals are constantly migrating from Russia to China and back, they said.