Police in the eastern Chinese city of Wenzhou, where the suspected hacking took place on the evening of August 1, said a 40-year-old IT engineer surnamed Wang was detained at Beijing's international airport on August 16.
Further investigation is under way, Wenzhou police said on their verified social media account on Sina Weibo, a Chinese version of Twitter.
No explanation was given for the delay in announcing the details of Wang's detainment.
Such images are almost never shown by media in China, where the Communist Party censors anti-government messages and references to incidents it deems sensitive such as the Tiananmen crackdown when the army killed hundreds -- by some estimates more than 1,000 -- protesters.
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One photograph showed the channel displaying the iconic "Tank Man" photo from the 1989 crackdown, showing a lone man standing in front of a column of tanks.
China's Communist party does not tolerate organised dissent, and has regularly jailed members of any group which challenges its right to rule the country.