Taipei: A serving Taiwanese police officer and a retired officer were interrogated by Chinese state security personnel in Fujian Province in June, as reported by the Mainland Affairs Council (MAC) on Thursday. The officers faced questioning regarding the organizational structure and lists of Taiwan's critical infrastructure. According to Focus Taiwan, the Chinese personnel were aware of the officers' previous employment at a specific government agency, although the agency's identity and the exact critical infrastructure discussed were not disclosed by MAC deputy head and spokesperson Liang Wen-chieh during a briefing in Taipei. Critical infrastructure in Taiwan is classified into nine sectors, such as energy, water resources, communications, and government agencies. The interrogation included examining the officers' mobile phones and inquiries about their family and personal details. Despite being released and returning to Taiwan, the officers were advised against reporting the incident to Taiwanese authori ties, Liang stated. Under Taiwan's Cross-Strait Act, individuals whose roles involve national security need central review committee approval for travel to China. However, lower-ranking civil servants and police officers are exempt from this requirement if their duties do not concern national security or classified matters. Liang noted that the serving officer's rank did not necessitate a review, and the retired officer had no post-retirement travel restrictions. Nonetheless, due to their previous involvement with critical infrastructure, a central committee review should have been deemed necessary. MAC plans to ask government agencies to tighten travel application reviews to prevent similar incidents. Liang also addressed the detention of four Taiwanese individuals traveling in China for unknown reasons, while five others remain unaccounted for. Families of the detained individuals received calls confirming their detention, raising concerns over their safety. The cross-strait joint crime-fighting mechanism 's current inefficiency compels Taiwan to rely on informal contacts within China for information, complicating the handling of such cases, Liang explained.