Kim "guided" the drill on Monday, KCNA said.

South Korea had said that North Korea fired what appeared to be two short-range ballistic missiles on Monday, but it was not immediately clear if the two incidents were the same.

"As he ordered the sub-units to start the fire, the men of long-range artillery pieces on the front opened fire all at once," KCNA reported.

The South Korean military said two devices were fired eastwards over the sea from the Wonsan area on North Korea's east coast and flew 240 kilometres (150 miles) at a maximum altitude of 35 kilometres.

They were "believed to be short-range ballistic missiles," a military official said.

The reported launch was the nuclear-armed North's first for more than three months and came as nuclear negotiations with the United States remain at a standstill.

Kim declared in November that Pyongyang no longer considered itself bound by its moratoriums on nuclear and intercontinental ballistic missile tests, and threatened to demonstrate a "new strategic weapon" soon.