North Korea has been developing a 3,000-ton class diesel-powered submarine since 2009, with the new type aimed at being capable of loading four of its new submarine-launched ballistic missiles (SLBMs), a researcher claimed on Wednesday.

During a bimonthly briefing held in Seoul, Kim Heung-kwang of North Korea Intellectuals Solidarity (NKIS) said the North had been developing a submarine that is bigger than Sinpo-class, the largest known North Korean submarine, for the last few years.