Updatet 5:20 p.m. ET on 2014-1-2
Authorities in the southern Chinese city of Shenzhen have detained prominent Hong Kong activist Yeung Hung on suspicion of illegally crossing the immigration border with neighboring Hong Kong, his wife said.
Hong Kong, China's Special Administrative Region, is a former British colony and still maintains an immigration border with the mainland.
Yeung, a political activist, is under criminal detention by Shenzhen police, according to Liu Linna, widely known by her pseudonym Liu Shasha.
Yeung's travel permit issued to Hong Kong citizens wishing to go to mainland China had been revoked by the authorities after he and Liu Shasha tried last February to visit Liu Xia, the wife of jailed Nobel peace laureate Liu Xiaobo under house arrest at her Beijing home.
"This is a violation of his human rights and a form of political persecution," said Liu Shasha, whose home province is Jiangxi in the mainland's southeast, and who married Yeung last August.
She said Yeung had been detained for several days before she was notified.
Yeung had also captained a converted fishing vessel that carried Chinese nationalist activists to the disputed island chain in the East China Sea where they were detained and deported by Japan in October 2012.
It is not immediately clear whether his latest detention is linked to his rights activism or to Beijing-Tokyo tensions over the disputed islands, known in Japan, which controls them, as the Senkaku and as the Diaoyu in Chinese..
Beijing-based rights activist Hu Jia said Beijing was keen to avoid doing anything to exacerbate tensions with Tokyo.
"They are afraid that if they don't keep certain people under control, that when they play the Diaoyu card, there could be chaos [in China]," Hu said.
Sichuan-based rights activist Huang Qi called on the Chinese government to respect the basic human rights of Diaoyu island activists.
"They should respect Yeung Hung's rights and allow him back into mainland China," he said.
Meanwhile, the Japanese coastguard on Thursday said it had rescued a Chinese balloonist, identified as 35-year-old chef Xu Shuaijun, near the disputed islands.
Xu had attempted to land his multicolored balloon amid high tensions over the disputed territory between the world's second- and third-biggest economies, and in the wake of Japanese Prime Minister Shinzo Abe's visit to the Yasukuni war shrine, where Japanese leaders convicted by the allies as war criminals are among the millions of enshrined war dead.
Chinese Foreign Ministry spokesman Qin Gang described Xu as a "balloon enthusiast," and confirmed he had been handed over to a Chinese vessel upon being rescued and was in good health. He declined further comment.
Xu's flight came as both countries repeatedly scramble fighter jets into the airspace around the disputed islands, and as Abe vowed once more to revise Japan's pacifist, post-war constitution and strengthen its military.
"Japan will play an even more proactive role than ever before for world peace and stability," Abe told the nation in a New Year message.
"We will fully defend the lives and assets of our nationals as well as our territory, territorial waters and territorial airspace in a resolute manner."
Sino-Japanese ties reached a new low after Beijing expanded its flight identification zone to cover the Diaoyu, or Senkaku, islands.
Beijing last month announced an air defense identification zone over the East China Sea and warned of unspecified "emergency defensive measures" against aircraft which do not notify it before flying there.
Japan has refused to comply, and has announced it will boost its military spending through purchase of early-warning planes, beach-assault vehicles, and troop-carrying aircraft.
Reported by Wen Yuqing for RFA's Cantonese Service. Translated and written in English by Luisetta Mudie.