As part of an undercover operation, immigration officers sold their own passports to syndicates that make as much as $30 million a year by reselling them to international snakeheads. Anti-Illegal Migration Agency chief Yim King-sum said the officers were taking part in their first undercover operation, codenamed Operation Sting, against such passport trading. All the passports were recovered and returned to the officers. It is the first time the Immigration Department, of which the agency is part, has revealed details about the operations, in which three officers arrested three passport brokers in separate raids. In hearings held from December to February, courts sentenced the three brokers, from two passport-buying syndicates, to terms of 26 months to three years. Two people who sold their passports were jailed for 16 months. The arrests came after the agency acted in response to newspaper advertisements placed by the syndicates seeking passports for cash. In one instance, the passport buyer almost escaped with the undercover officer's passport by jumping off an MTR train. 'The passport broker asked to meet our undercover colleague at the Telford Plaza, where he inspected the officer's passport,' a spokesman said. 'But instead of completing the transaction, he demanded the officer follow him to the nearby MTR station.' The undercover officer agreed, and the team of supporting officers had to quickly leave their positions to track him and the passport buyer through the MTR system. 'After boarding a train towards Choi Hung, the man gave the officer $1,000 - but again he didn't take the passport. Then suddenly, just as the door was able to be shut for the train to depart Choi Hung station, the man snatched the passport and jumped out of the train between the closing doors.' Only one officer managed to jump off. He was left to tackle the broker alone, while his colleagues ended up at Diamond Hill and had to catch the train back to the scene. The broker, 38-year-old Cheung Wai-ming, was jailed for 26 months in January. The court was told that for his troubles Cheung received only $50 for each passport.