Taipei, Taiwan (CNN)A Taiwanese soldier who went missing last week from an island near the Chinese coast has been found in mainland China, a Taiwan official said on Monday, raising the possibility of a highly unusual defection amid heightened tensions across the Taiwan Strait.
Speaking to reporters, Chiu Tai-san, minister of Taiwan's Mainland Affairs Council, said China had notified Taiwan that the soldier, surnamed Chen, is currently in mainland China.
Chen was reported missing on Erdan island following a roll call, the Taiwanese Defense Ministry said in a statement Thursday, adding it had set up a special task force to locate him.
Erdan, part of the Taipei-controlled Kinmen islands, is located less than 5 kilometers (3.1 miles) from the Chinese port city of Xiamen in southeastern Fujian province.
In recent years, Beijing has ramped up economic, diplomatic and military pressure on Taiwan -- a self-ruling democracy the Chinese Communist Party claims as its own despite having never governed it.
China's People's Liberation Army (PLA) frequently sends aircraft and warships close to Taiwan, in a campaign aimed at intimidating the island and wearing down its equipment.
On Monday, Chiu said the Taiwanese Defense Ministry has existing mechanisms to determine whether the soldier should be identified as a deserter.
He added that the Taiwanese and Chinese sides have communication channels to handle emergency situations and combat crime. "The defense ministry and coast guard administration are actively understanding the relevant progress and situation," Chiu said.
CNN has reached out to Taiwan's Defense Ministry for comment.
While defection between the two sides has been rarely heard of in recent years, it used to be a more common occurrence.
In 2002, Taiwan's then-minister of defense said the Taiwanese military saw 20 cases of defections to China between 1949 and 1989.
Defectors from both sides were seen as huge propaganda wins -- and sometimes rewarded in cash.
In 1981, China paid a reward of $370,000 to a Taiwanese Air Force major who defected to the mainland with an American-built reconnaissance plane -- a valuable asset for the PLA at the time.
Other defectors would swim between China and Kinmen. The closest distance between the main island of Kinmen and the Chinese coast, at low tide, is less than 2 kilometers (1.6 miles).
In 1979, Justin Lin, a Taiwanese ground force captain and company commander, swam across that channel to defect to China. He went on to study at the prestigious Peking University and become a high-profile economist.