"The North has launched an unidentified ballistic missile toward the East Sea," it said, referring to a body of water also known as the Sea of Japan.

Japan's defence ministry also said it detected a possible ballistic missile, which landed in an unspecified location around 8:08 am (2308 GMT Saturday).

North Korea last staged a ballistic missile test in November, after US President Donald Trump approved South Korea's plan to build a nuclear-powered submarine.

Pyongyang has significantly stepped up missile testing in recent years.

Analysts say this drive is aimed at improving precision strike capabilities, challenging the United States as well as South Korea and testing weapons before potentially exporting them to Russia.

Pyongyang is also set to hold a landmark congress of its ruling party in the coming weeks -- its first in five years.

Economic policy, as well as defence and military planning, are likely to be high on the agenda.

Ahead of that conclave, leader Kim Jong Un ordered the "expansion" and modernisation of the country's missile production and the construction of more factories to meet growing demand.

On Sunday, state media reported that Kim had paid a visit to a facility involved in making tactical guided weapons.

And he ordered them to expand current production capacity by 250 percent, the state-run Korean Central News Agency (KCNA) said.

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