The man's wife, Komila Telindieva, said her husband was arrested on March 27 in Tashkent on the basis of Kyrgyz and Chinese Interpol warrants.
Sarvar Usmon, a relative, told RFE/RL's Uzbek Service that Celil was once an imam in China's western Xinjiang region. He now faces possible extradition to China.
"I have spoken to his wife recently," Usmon said. "As far as I know, officials in Tashkent are now waiting for some document from Beijing. And only after they get that document will his fate be decided. Primarily, Huseyin Celil was an imam in East Turkestan. Soon after, he started an ideological fight for the independence of East Turkestan."
Some Muslim Uyghurs -- the majority in Xinjiang region -- are seeking an independent state they call "East Turkestan."
An official from the Canadian Embassy in Moscow said officials are working on the matter.
The man's relatives are concerned he faces possible torture and execution if he's extradited to China.
(with additional material from AFP, Canadian press)