Authorities in Vietnam detained for questioning a dozen young activists on their return from a training stint with a civil society organization in the Philippines amid suspicion in Hanoi that they might be involved in anti-government activities, according to friends and family. The 12 youths had attended the two-week 2013 Civil Society study program with rights organization Asian Bridge Philippines in Manila and were taken into police custody in three separate groups on their return to Vietnam, beginning late last week. "When I arrived at the airport, there were many policemen, which I already anticipated," said blogger Bui Tuan Lam, among four activists held at the Ho Chi Minh City's Tan Son Nhat Airport after deplaning on Oct. 5. "[They] took me to a room at the airport with seven or eight people in it ... and kept me there for 16 hours," Lam told RFA's Vietnamese Service. The others held with him included blogger Yeu Nuoc Viet and activist Tran Hoai Bao. "They asked me ... about the course, how many people attended, who organized it, if I knew that "hostile forces' were behind it ... I told them I didn't care about that[and that] all I cared about was that it was a good course about civil society, which is very weak in our country." The second group of five was detained on Oct. 6 at Hanoi's Noibai Airport and included Do Van Thuong, Nguyen Viet Hung and Dang Hai Di, while the third group detained two days later at Tan Son Nhat Airport comprised Pham Tran Quan, Truong Quynh Nhu and Bui Thi Dien. All nine activists detained in the first two groups were released late in the evening on Oct. 6 while the third group was released on Thursday, Lam said. He said the 12 had met with Philippine NGOs and lawmakers, and representatives of the United Nations' Office of the High Commissioner for Human Rights and the Asian Development Bank. He said that he decided to return home although he learned about the detention of some of his colleagues earlier "because I did not do anything wrong-I only went to learn some new things for the benefit of our country." Told to sign Lam said that his interrogators treated him well but repeatedly asked him to sign documents, including photos of people who attended the course and a letter asking for leniency. "I did not sign because it wasn't right ... I only signed to acknowledge the minutes of the meeting, but I would not sign any other document promising that I would not attend any similar courses or make public the content of our meeting," he said. "They said civil society is good, but as it develops there will be interest groups and parties which[will call for the] overthrow of the regime ... I told them that their argument is ridiculous. Nobody is against them and if they do good things the people will support them." He was finally informed he would be "summoned again when needed" before being freed. "Committed to learn' Asian Bridge Philippines had expressed concern in a statement that the Vietnamese government had decided to detain the 12, saying the group found it "unsettling" that they were held "without any explanation or notice." "To Asian Bridge Philippines, it is highly commendable that these young individuals from Vietnam are committed to learn about what civil society means and how it has developed in the Philippines," the statement said. It urged the Vietnamese authorities to respect the "basic rights" of all Vietnamese "to freely travel and learn about the development of civil society in other nations in the region." The group said that as part of the Association of Southeast Asian Nations (ASEAN) bloc of ten nations, Vietnam should "encourage their citizens to learn about other nations' history and society, instead of instilling fear, so that the mission of ASEAN can be soon achieved." Aside from Vietnam, ASEAN comprises Laos, Brunei, Cambodia, Indonesia, Malaysia, Myanmar, the Philippines, Singapore, and Thailand.