The BBC is protesting to the Chinese Government over the jamming of its short-wave broadcasts in the Uzbek language.
The Director of BBC World Service, Mark Byford, said the corporation was protesting to China in the strongest possible terms.
Although there is no significant Uzbek population in China, the Uzbek language is very close to that spoken by Islamic Uighurs, who make up more than half the population in China's western province of Xinjiang.
Uighur groups have long been agitating for independence for Xinjiang, or as they call it East Turkestan.
BBC blackout
The latest Chinese action has prevented Uzbek speakers, most of them outside China, from hearing broadcasts in their own language.
BBC field tests have confirmed regular jamming since 1 September.
It consists of a strong radio signal from a Chinese station on three frequencies.
Engineers say it consists of the same music, with gongs and string instruments, played over and over again.
China has been jamming the BBC's Chinese broadcasts since the suppression of protests in Tiananmen Square in May 1989.
Recently, the BBC's English and Chinese internet sites have been blocked for users in China.
East Turkestan issue
There were regular reports of unrest in Xinjiang throughout the 1990s.
The province was torn by demonstrations, mass arrests, sporadic gun battles between rebels and Chinese forces and a number of bombings of buildings and buses.
Attacks on civilian targets led the United States in August to include the East Turkestan Islamic Movement to its list of terrorist organisations.
The move pleased China but has caused concern among human rights organisations.
They say there is evidence that the Chinese authorities are using the current international climate to clamp down further on the legitimate human rights of Xinjiang's Muslim population, including their right to listen to foreign broadcasts.