HARBIN, Oct. 10 -- The second of three rare tigers set free by Russian President Vladimir Putin was found wandering around the Sino-Russian border, following another that reportedly roamed into China, an insider told Xinhua on Friday.

The Siberian tiger, Ilona, was observed at a location less than five km from the Heilongjiang River along the Sino-Russian border, said Eugene Simonov, coordinator with Rivers without Boundaries Coalition, a multinational non-governmental organization.

Simonov said he received a message from Russia on Thursday morning and the tiger, tagged with a tracking device, was found moving toward China over the previous three days.

It remains unclear whether Ilona has entered China like Kuzya, another Siberian tiger that allegedly roamed into China earlier this month after it was released into the wild by Putin in May.

Simonov said that if Ilona crosses the border, it will likely reach somewhere with more humans but less food compared to Kuzya's observed location at the Taipinggou nature reserve in Luobei County in northeast China's Heilongjiang Province.

Possible traps are a major danger for Kuzya, he said. Chen Zhigang, director of the nature reserve, said on Thursday that personnel had been dispatched to remove traps and set up more than 60 cameras in the hope of capturing the tiger's image.

Simonov said parties in the region should have a contingency plan as soon as possible in case the tiger is trapped.

Fewer than 500 Siberian tigers remain in the wild, mainly in eastern Russia, northeast China and northern parts of the Korean Peninsula. China puts its own number of wild Siberian tigers between 18 and 22, mostly living in the border areas.

Simonov and zoologists have called for establishing a nature reserve on the Sino-Russian border to prevent inbreeding among the endangered species.

"We have been talking about the cross-border nature reserve for years. It would be highly conducive to the protection of Siberian tigers," Simonov said.

Wildlife expert Ma Jianzhang, who is also an academician with the Chinese Academy of Engineering, said it is not uncommon for wild Siberian tigers to cross the border. "Most tigers settle in Russia, and some come to China for food because competition here is not that fierce."

According to Ma, a tiger in Russia swam across the Wusuli River into China in June. In the winter, the big cats are able to cross the border more easily via the frozen river surfaces, Ma said.

Ma said a major obstacle for the tigers' cross-border activities is barbed wire set up to prevent illegal border crossing. He suggested wire located on the tigers' migration channels be removed.