BEIJING (Reuters) - Hu Jia, a well-known Chinese dissident who lives in Beijing, says he had hoped to go to the southeastern city of Xiamen for his government-sponsored holiday, but state security officials said no.   They told me I had to go to a more isolated place this time,  he told Reuters by phone from Yunnan province in far southwestern China, a popular destination renowned for its scenery and the culture of its ethnic minority groups. Rights groups say that Hu is one dozens of activists and dissidents detained, placed under tighter monitoring or  vacationed  by authorities,  during the week-long congress of the ruling Communist Party which began on Wednesday in Beijing. President Xi Jinping is expected to tighten his grip on power at the gathering, which is only held once every five years. For his enforced holiday, Hu and his two government minders jointly decided on the destinations. Hu suggested the ancient town of Dali in Yunnan for the first stop, and the public security agents accompanying him chose the second and third stops in the southwest region, Guiyang   the capital of the mountainous province of Guizhou, and the coastal city of Beihai in Guangxi province.  Hu estimated the whole trip for the three of them will cost close to 10,000 yuan ($1,510), all paid for by the authorities. He said that his minders tried to save money by choosing basic hotels and traveling between the three cities by bus. He will fly back to Beijing on Oct 28, just after the congress ends.  You can go see the sights, but state security goes with you everywhere,  Hu said. Reuters was unable to independently verify the accounts of Hu and other dissidents interviewed for this story. China s public security ministry did not respond to a faxed request for comment on the detention of activists, and the use of  vacations.  China rarely explains its treatment of dissidents other than to say that those charged are criminals who harmed social stability and that all people in China are treated equally before the law. It is not unusual for Chinese authorities to heighten monitoring and detention of dissidents before important political events, especially people with high profiles who are  known to speak out against the party and state. In addition to the enforced vacations, some activists have also been detained, placed under supervision at home, or warned about posting critical messages online in the weeks ahead of congress, according to the Hong Kong-based group Chinese Human Rights Defenders.  The group also said it had documented 14 cases of detention of activists in recent weeks. In one case, Wu Kemu, a truck driver from Xuancheng city in the central province of Anhui, was called in by the police for a talk on October 11 and has not been released since, his wife Fang Liangxiang told Reuters by phone on Sunday.  They will not say when he will be released. They just told me to wait at home for him,  she said, adding that she expected the detention was related to critical things Wu had said about the government on the popular instant messaging platform WeChat. No one answered the phone on Saturday at the Xuancheng city detention center where Fang says Wu is being held. It is unclear if the total number of detentions, arrests or  vacations  this year is greater than at the time of previous major events or how many of the cases are directly related to the congress. Some activists say that the authorities prefer enforced vacations rather than detentions as they can make dissidents both inactive and inaccessible to foreign journalists over sensitive periods. Locking people up can attract more attention. Hu, a pro-democracy activist and campaigner for those with HIV/AIDS, was sentenced to three-and-a-half years in jail for subversion in 2008, and said he has been under regular state surveillance since his release.  The first thing I did was go for a run up in the mountains by Dali, because I knew the state security agents could not run with me,  he said, adding that the agents were  not the running type.   It felt like being briefly free from prison,  he said. Hu said that state security agents had shown him a list of people who would not be allowed to stay in Beijing over the 19th Party Congress, including Liu Xia, the widow of Nobel Peace Prize winner Liu Xiaobo.   Liu Xia has been under effective house arrest in Beijing since her husband won the Nobel Prize in 2010. After his death in July, even the sporadic communications she s had with friends have been nearly entirely severed, two of them told Reuters. The public security ministry did not respond to a request for comment on Liu Xia s situation. Some activists make their own travel plans to avoid the authorities. Wu Lihong, an activist from Wuxi city in Jiangsu province who for over a decade has been protesting pollution in Lake Tai in eastern China, told Reuters that Chinese state security had called him last week saying they were coming to take him for a forced vacation. Wu, though, had already gone to visit a friend in Zhejiang province, on the east coast and far away from Beijing, to avoid them.  At the 16th, 17th and 18th Congresses I was vacationed, imprisoned, held at home and forbidden to speak,  Wu said.   This time, I chose to go on holiday without them,  he said. He said that state security officials had asked him to return to Wuxi so they could take him on  vacation  themselves, but he declined saying he would stay with his friend till after the congress ends. He is now avoiding their calls. Reuters could not independently confirm Wu s comments. Chinese state security does not have a public phone number, fax number or website.     Xi has overseen a sweeping crackdown on rights lawyers and activists since coming to power in 2012, jailing dozens, in what rights groups say is a coordinated attempt to quash dissent in China. New internet measures include rules that hold users accountable for critical posts even in private group chats and a renewed crackdown on technologies to circumvent restrictions.  Kit Chan, director of the Hong Kong-based China Human Rights Lawyers Concern Group, said that some recent detentions of activists represent a new direction in the crackdown as it shows the authorities are targeting smaller groups that draw attention to specific rights issues as much as their traditional focus on pro-democracy activists. Zhen Jianghua, for example, the founder of Human Rights Campaign in China, a grassroots organization based in the southern province of Guangzhou, was detained on Sept 1 in Zhuhai, a source close to Zhen who declined to be named told Reuters. The ministry of public security did not respond to a faxed request for comment about the targeting of grassroots organizations. A person who answered the phone at the Zhuhai public security bureau said she was not aware of Zhen s case. 