The tests, previously reported by South Korea's military, were overseen by the North's leader, Kim Jong Un, the state-run Korean Central News Agency (KCNA) said.

South Korea said on Tuesday the North fired several projectiles, including a ballistic missile, off its west coast, the latest in a flurry of tests this year. Seoul said the missiles flew about 80 kilometres (50 miles).

Analysts have said that by conducting a series of missile tests in recent months, Pyongyang may be trying to take advantage of eroding international norms to cement its nuclear status.

Tuesday's launch "analyzed and estimated the power of special mission warhead of tactical ballistic missile, the reliability of 240mm controlled artillery rocket with expanded firing range which employed an ultra-precision autonomous navigation system," KCNA said in an English dispatch.

North Korean leader Kim noted that the "major weapon systems are a clear signal of upgrading of our military force and an event of showing great technical progress," KCNA quoted him as saying.

"It is essential condition for our army's operations to have such destructive power as enough to make any encountering force impossible to survive theoretically, apart from fortune," he added, according to the report.