"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 had detected a suspected ballistic missile launch.

North Korea 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.