Mak Yin-ting, chairwoman of the Hong Kong Journalists Association, told Sunday's gathering that Chinese officials had 'crossed the line' and must account publicly for their actions.

Hong Kong, a former British colony, has a free press and enjoys freedom of speech as well as political and judicial autonomy denied to people elsewhere in mainland China.

Tensions between Xinjiang's ethnic Uighur and Han Chinese residents climaxed in July with bloody clashes in Urumqi that left at least 197 dead and more than 1,000 injured.