Taipei: Taiwan has detained a retired Air Force captain and three active military officers in the city of Kaohsiung on suspicion of spying for China, the Taiwanese Central News Agency reported on Thursday, citing the Kaohsiung Branch of the Taiwan High Prosecutors Office.

As many as seven individuals were brought for questioning on Tuesday, with three of them having been released on 100,000 to 200,000 new Taiwan dollars (USD 3,260) bail, Taiwan Focus reported.

After the questioning, the prosecutor's office filed a motion to detain the retired Air Force captain surnamed Li, a commander surnamed Sun, and two lieutenant commanders identified by their surnames Liu and Kung .

Liu began doing business in China after retiring from the force in 2013 and then was recruited by Beijing as a spy to recruit active military officers in the Navy and Air Force, the media cited prosecutors as saying.

Liu is believed to have recruited at least six military officers for "rewards" of between 200,000 and 700,000 new Taiwan dollars from Beijing through a shell company.

The Taiwanese media also cited its National Defence Ministry as saying that the case was exposed by the military personnel who took the initiative to investigate the espionage allegations.

The investigation into the case is ongoing as more military personnel are believed to be involved in spying activities for China.