An outspoken Vietnamese blogger has been attacked by knife-wielding thugs after he took part in an anti-China rally in Hanoi amid a government crackdown on activists who attended the rare public demonstrations. Catholic blogger Nguyen Huu Vinh said a group of local thugs came to his house in Hanoi's Giap Bat precinct on Sunday after he came from the demonstrations. "They charged into my house to beat me and slash me with a large knife right after I was at the anti-China demonstration," Vinh told RFA's Vietnamese service. Vinh received cuts on the neck, back, chest, and hands before neighbors responded to his calls for help and the thugs ran away. He said the ringleader of the group was the son of the head of a neighborhood committee, the lowest level of local government administration. "They were not police, but a group of thugs organized by the local urban population group head Nguyen Xuan Ky's son," he charged. The charge could not be immediately verified with the authorities. Vietnamese authorities have harassed other netizens and activists who participated in or tried to attend the anti-China rallies in Hanoi and Ho Chi Minh City on July 1 and 8. Public demonstrations are rarely allowed in Vietnam and the rallies, sparked by territorial disputes in the South China Sea, have been led by dissidents and activists. Vinh, a former policeman in his mid-50s, said he called local police twice for help and to report the incident but that they arrived at his home after a long delay. The Giap Bat precinct deputy police chief was at the scene and submitted a report that evening, followed by other police personnel the next day, Vinh said. Vinh said he had never had any personal conflicts with the attackers and did not know why they would go after him. He warned police not to allow impunity for those who act illegally against him and his family. "When working with the Giap Bat precinct police, I made clear that I strongly protest any action of harboring individuals ... who threaten me and threaten my life or spy on my family and invade our privacy, among other things," he said. Vinh, who blogs about social injustice, official corruption, and Hanoi's response to Chinese "aggression" in the South China Sea, has been questioned more than 30 times by the authorities over his writing, including by the Ministry of Public Security. Vinh said that on those occasions he told the authorities his writing is truthful and it would be illegal to make him stop. "All of my writings are based in truth and reality. If you want to prohibit me from writing these realities, you should get the National Assembly to promulgate a law banning people from telling the truth. Then I'll abide by that law," Vinh said. "I want to live in a society under a state of law in which everything must be clear and transparent," he added. Vinh is a member of the Archdiocese of Hanoi and many of his articles have documented on repression of Roman Catholics in Vietnam, including Hanoi's Thai Ha parish. His blog was hacked in 2010 amid a series of cyberattacks on dissident websites that media watchdog Reporters Without Borders said may have been part of a government crackdown. He has witnessed, blogged about, and posted photos of religious crackdowns and land seizures, as well the anti-China rallies this year and last year. He said that despite efforts to intimidate him he would not stop attending the demonstrations. "I feel moved when seeing posters held high by my fellow anti-China demonstrators expressing their patriotism. I believe that every Vietnamese citizen has that obligation and I myself also have such an obligation, so I continue to take part in the demonstrations," Vinh said. Fellow blogger Huynh Thuc Vy, from Vietnam's Quang Nam province, was detained by police and driven from Ho Chi Minh City to her hometown after attending a rally the week before. Several other bloggers said they had been prevented from attending the demonstrations. Last year, authorities allowed the first of the anti-China demonstrations to go ahead without disruption, but detained dozens of participants at later protests following talks between Hanoi and Beijing. The attack on Vinh came as New York-based international watchdog Human Rights Watch (HRW) called on U.S. Secretary of State Hillary Clinton to press Vietnam for the release of prominent bloggers during her visit to Hanoi on Tuesday. The country has imprisoned more than a dozen bloggers and activists in the past three years for using the Internet to promote their causes and express their opinions, the organization said. "Vietnam continues to harass, intimidate, arrest, and imprison bloggers and online activists" who are exercising their basic rights of expression, it said.