North Korea recently completed a large dock capable of building 10,000-ton-class submarines in a shipyard in Sinpo, South Hamkyong Province, a US broadcaster, monitored in Seoul, reported Friday.

"In accordance with North Korean leader Kim Jong-un's instruction to build a 10,000-ton sub in 2014, the existing dock in Sinpo was expanded of late," Radio Free Asia said, citing a North Korean source.

The shipbuilding dock is 180 meters long and 25 meters wide, the source said.

A shipbuilding dock in North Korea (Yonhap)
A shipbuilding dock in North Korea (Yonhap)

Experienced engineers and technicians working at a shipyard in Chongjin, North Hamkyong Province, along with their family members, also have moved to Sinpo to build submarines, according to the source.

Apart from that, two 3,000-ton-class subs are currently under construction at the shipyards in Sinpo and Chongjin, the source said. (Yonhap)