SEOUL - _ Republic of Korea (ROK) officials on Thursday criticized a Democratic People's Republic of Korea (DPRK) artillery launch that they say happened minutes before a Chinese commercial plane reportedly carrying 202 people flew in the same area.

It wasn't immediately clear what danger, if any, Tuesday's launch  posed to the China Southern Airlines plane traveling from Tokyo to Shenyang, China, but Seoul Defense Ministry spokesman Kim Min-seok called it a "serious threat" that Pyongyang failed to notify international aviation authorities of its launch plans in the area.

Kim said the plane was traveling at an altitude of 10 kilometers, while the projectile's peak altitude was 20 kilometers. He said the flight passed through the area about five minutes after the projectile hit the water.

It was not immediately clear what kind of artillery the DPRK launched. But ROK officials believe the recent series of launches were in part an effort to test 300-mm multiple rocket launchers.

An unidentified DPRK army spokesman said in a statement on Wednesday night that rocket drills conducted from Feb 21 until Tuesday were part of regular training. He said that neither regional security nor the international navigation were in danger because the DPRK took "scrupulous advance security measures for flight orbit and targets in the designated waters."

Asked about the incident, a Chinese Foreign Ministry spokesman called for all sides to continue improving relations and to refrain from provocations.

Qin Gang said no specific matters related to China's civil aviation safety were reported on Tuesday. But, "we will check the situation with relevant parties and express our concern which is necessary."

"I want to stress here that we attach great importance to the security of China's civilian flights," Qin Gang said at a regular press briefing.

"If any country is to hold training or exercises, it should take measures in accordance with international practice to ensure the safety of civil (facilities) in relevant airspace and maritime space," Qin said.