A former Taiwanese air force officer has been given 12 life sentences for spying for the mainland, adding to a long list of espionage cases that have rocked the island. Lieutenant Colonel Yuan Hsiao-feng was convicted of passing unspecified military secrets to the mainland between 2001 and 2007. He handed the secrets to the mainland via retired colleague Chen Wen-jen. Both men were sentenced on Tuesday, with Chen receiving a 20-year jail term. Yuan was found guilty of 12 counts of leaking secrets, each of which carries a mandatory life term. The duo, who can appeal against the ruling, have been detained since last year when they failed to recruit two junior colleagues, who turned them in to the authorities. The Taipei-based China Times said Yuan was paid NT$7.8 million (HK$2.04 million) by Beijing for the secrets he collected. Taiwan and the mainland have spied on each other ever since they split in 1949. Taiwan has been rocked by a string of spying scandals in recent years, reflecting the fact that intelligence gathering has continued despite warming ties with the mainland. In 2011, an army general and chief of an intelligence unit was sentenced to life for spying for the mainland in one of the island's worst spy scandals. A Taiwanese admiral has been questioned over his alleged involvement in an espionage case that led to the arrest of three senior military officers in September for spying for the mainland, officials said this week.