Two mainland activists were sentenced to terms in a labour camp because they took part in Hong Kong's July 1 protest march, according to the written judgment in a trial conducted by police. Hong Kong rights groups said it was the first time mainland activists had been punished for taking part in the city's annual march, and the first time an official document had called such participation an offence. Activists Song Ningsheng, 44, and Zeng Jiuzi, 53, will serve 14-month terms in a labour camp in Ningdu county, Jiangxi province. They were initially detained in the county's police station two weeks ago, after petitioning in the July 1 rally and later in Beijing, outside Tiananmen Square and the Zhongnanhai district. The first page of the two-page judgment, seen by the South China Morning Post, said: 'After a trial and clear investigation, [it was found] Song Ningsheng and Zeng Jiuzi went to Hong Kong in late June. They took part in protests during activities commemorating the anniversary of Hong Kong's handover on July 1.' It also said the activists had petitioned in Beijing on July 9 and July 11. Furthermore, Zeng's son, Liu Zhonghua , told Voice of America that police informed him that his mother was being punished for taking part in an 'anti-China' protest in Hong Kong. Liu Weiping , chairman of the Hong Kong-based People's Rights Union of China, who organised the duo's trip to the city, said it was the first time mainland activists had been punished for protesting in Hong Kong. Security personnel stalked the pair in the city, he said. Liu said: '[Unless there is] democracy in [mainland] China, there will not be any in Hong Kong. If these mainland security personnel prevail, what does it mean to Hongkongers? They really should think about it.' A member of the People's Rights Union visited the two activists at the labour camp, and secretly took a photo of the judgment's first page. The union member was only allowed to see Zeng, who was said to be in good shape. Liu thinks Song has been tortured at the camp. Song and Zeng were petitioning about the deaths of their spouses. This year's march was sensitive for Beijing since one theme was the suspicious death of June 4 dissident Li Wangyang , according to the Civil Human Rights Front, which has organised the event for the past decade. 'It is sending out a very strong message, threatening mainlanders not to learn the protest culture from Hong Kong people,' said Eric Lai Yan-ho, the front's convenor.