Human rights activists and family of Huseyin Celil are calling on Ottawa to put more pressure on China to reveal where the 38-year-old Canadian citizen is being imprisoned.

Celil, a Muslim and member of China’s Uighur minority group, was sentenced to life in prison by a Chinese court last April. A year earlier, he had been arrested in Uzbekistan and extradited to his native China to face terrorism charges.

Celil's whereabouts in the Chinese prison system are unknown to his family and Canadian officials. His southern Ontario-based wife and children have sent a letter to Prime Minister Stephen Harper urging him to intensify pressure on Beijing to provide more information. 

"Prime Minister, we call on you to renew and fortify Canada's efforts to ensure Mr. Celil's human rights are protected," the letter says. 

In the message to Harper, the imprisoned man's family expresses concern that "Canda’s attention to Celil's fate appears to have waned."

The prime minister has raised Celil's case with Chinese authorities at the highest level, telling President Hu Jintao in November of 2006 that "when a Canadian citizen is taken from a third country and imprisoned in China, this is a serious concern to this country."

During a visit to Beijing last April, then foreign minister Peter MacKay sought assurances from Chinese officials that Celil wasn't tortured during his interrogation and imprisonment. Chinese officials told MacKay that the Canadian hadn't been tortured, although his family says that he has been brutally maltreated.

'Deeply disappointed' MacKay

MacKay later told journalists that he expressed his "deep disappointment" about the case to his Chinese counterpart.

China has consistently refused Canadian officials consular access to Celil, who has been a citizen of Canada since 2005 after arriving in the country as a refugee in 2001. China contends that Celil has no right to consular access because, as a dual citizen, he is subject to Chinese laws. However, usually China automatically rescinds citizenship for people who take up nationality in foreign countries.

The case against Celil charged that he had been involved in violent separatist activities against the Chinese state. His friends, family and supporters say he was a human rights activist speaking up on behalf of an oppressed minority.

The Chinese Communist Party government takes the view that activism on behalf of ethnic minorities is often akin to separatism, as in the case of Tibet, as well as the Uighurs of Xingiang province.

There have been several violent attacks in China blamed on Uighur separatist groups, some of whom have ties to international Islamist political movements.

With files from the Canadian Press