North Korea has about 130 readily deployable hovercraft in its coastal waters, and its leader Kim Jong-un has regularly observed amphibious assault trainings targeted at South Korea, the Joint Chiefs of Staff (JCS) here said Tuesday.

North Korea has 70 deployable air-cushion vehicles on its west coast and 60 of the amphibious vehicle in the east at its four hovercraft bases, the JCS said in a report to the parliament.

The hovercraft can carry about 40 commandos at speeds of up to 96 kilometer per hour, making South Korean border islands less than an hour ride away.

Goampo base in South Hwanghae Province, which was built in early 2012, is only 50 kilometers from South Korea's northernmost island of Baengnyeong and 40 kilometers from the western sea border, called the Northern Limit Line (NLL).

In March when inter-Korean tension was running high, North Korea's leader visited the bases on its east and west coast, and observed amphibious landing operations involving the hovercraft.

The communist nation has regularly carried out landing operations using the amphibious vehicles, which Seoul officials believe are aimed at infiltrating the inter-Korean sea boundary to quickly occupy South Korean border islands in case of war.

Rep. Chung Hee-soo of the ruling Saenuri Party raised concern over the possibility of infiltration through the sea route and called on the South Korean armed forces to closely monitor the movements by the North Korean military.

"North Korea has built a hovercraft base near the NLL, and Kim Jong-un has regularly observed landing operations," Chung said.

"Considering this, it is very likely that North Korea may launch provocations using the air-cushion vehicles."

In 2010, the North shelled the front-line island of Yeonpyeong and sank a South Korean Navy corvette near the tensely guarded western sea, killing 50 South Koreans. (Yonhap News)