The Canadian Broadcasting Corporation has formally complained to China's ambassador to Canada about the continued blocking of the broadcaster's websites in China.

CBC president Hubert T. Lacroix outlined his concerns in a letter to Ambassador Lu Shumin on Friday.

Access in China to CBC's French-language website Radio-Canada.ca has been blocked for six months, while access to the English site CBC.ca has been cut off since January, Lacroix said.

"I am writing to request that you make formal and immediate enquiries as to why the sites have been blocked, and that you take steps to ensure that this policy is reversed," Lacroix said in the letter.

CBC News was informed that there will be no response from Chinese authorities on Friday because they are observing a holiday.

He quoted Chinese Premier Wen Jiabao, who last year said China's government would "provide services of an Olympic standard to athletes, officials, spectators and the media in order to facilitate their participation and enjoyment of the Games."

CBC is the official Canadian broadcaster of the 2008 Summer Games, which begin in Beijing in early August.

Canada and China's relationship depends on the ability to communicate, Lacroix said.

"Blocking access to our websites is inconsistent with that history and with China's growing place on the world stage," he wrote.

"I would appreciate your personal commitment to resolving this problem as quickly as possible and ensuring that access to our programming is restored expeditiously."

CBC News publisher John Cruickshank said restricting the broadcaster's websites is a violation of basic principles of free media and free press.

"It restricts the rights of all Canadians living in China, it restricts the rights of Chinese to get Canadian news and culture," said Cruickshank.

Blogs buzzing about move

CBC.ca is one of the most-viewed news websites in Canada.

Blogs have been buzzing about the CBC blockage for weeks.

"I'm not exactly sure why the site is blocked, but I'm annoyed about it. I first experienced this on Feb. 1, but thought it was a one-day thing," wrote John Guise on a blog called Zhongnanhai.

Ralph McGreevy, a Canadian teaching in China, said he can get most other news websites.

"Unfortunately, I still cannot get the CBC website, which is completely blocked. Most other news websites are reachable, although sensitive articles may not be," he wrote on a New York Times blog.

China has regularly blocked Western websites within its borders, and just recently lifted a ban on access to the British Broadcasting Corporation.

Human rights groups have criticized China for its strict censorship policies, but the government says filtering subjects it considers pornographic or subversive protects its citizens from harmful content on the internet.

With files from the Associated Press