Three North Korean MiG-19 fighters have crashed this year, leading to the suspension of flight drills involving the aircraft, South Korea's military sources said Wednesday.

The supersonic MiG-19 aircraft is a Soviet second-generation fighter developed in 1953. Some 400 MiG variants are still in service in the communist North, accounting for about half of its fighters.

"At least three of the MiG-19s crashed during training missions -- one earlier this year, the others last month and earlier this month -- apparently due to their aged fuselages," a source said, declining to be identified.

"In the latest case, the plane crashed right after taking off at the North's air base in Goksan, Pyongan Province, which led Pyongyang to stop drills involving the model," he added.

Other details about the accidents, including casualties, were not available.

It is "far from unusual for North Korea's fighters as well as military choppers to crash," another source said, noting frequent accidents "are partly behind its leader Kim Jong-un's inspection tours to the air force units this year."

In May, the young leader of the communist country visited the Korean People's Army's Air and Anti-Air Force Unit 447, presumed to be located in South Pyongan Province.

"The series of visits to the air force units or events seems to be aimed at not only countering the annual joint Max Thunder air drills between South Korea and the United States in April, but to encourage airmen demoralized by crash accidents," the source added. (Yonhap)