Three of the men, who were on a canoe trip down the Yurungkax River in a remote area of the Kunlun Mountains, were earlier found dead. The joint Russian-Chinese search operation for the remaining two group members continues.
The source said the survivor "lived for 25 days with almost no food, in fear of his life."
Alexander Zverev, whose date of birth was given as 1972, has been flown by helicopter to Hotan, in the Xinjiang autonomous area, and hospitalized. The source said his condition was severe, but not critical.
He was found on the bank of the Yurungkax, near the group's abandoned canoe, which had been spotted from the air.
The group of six set off on August 21 but failed to meet their interpreter as agreed on September 2.
On September 6, the Russian Canoe Federation requested help from the Russian Embassy in China to find the missing canoeists. Over 1,000 rescuers have been involved in the search. The joint Russian-Chinese rescue operation was interrupted on Monday due to a sandstorm, but resumed the following day.
Earlier, China's Xinhua news agency quoted a local Russian-language interpreter as saying the Russians might have been swept away by landslides or attacked by bandits who operate in the area. The agency said the youngest missing tourist was 25, and the oldest 47.
The three bodies discovered last Saturday and Sunday have been identified as Sergei Chernik and his son Ivan, and Vladimir Smetannikov. The search continues for the remaining two members, Dmitry Tishchenko and Andrei Pautov.
