North Korea said yesterday it had successfully test-fired a ballistic missile from a submarine, a step that would mark significant progress in the secretive state’s military capabilities.

It could pose a new threat to South Korea, Japan and the United States, which have tried to contain North Korea’s growing nuclear and missile strength, military experts said.

The North’s leader, Kim Jong Un, oversaw the test-launch from an offshore location as the submarine dived and “a ballistic missile surfaced from the sea and soared into the air, leaving a fiery trail of blaze,” the official KCNA news agency said.

“Through the test, it was verified and confirmed that the underwater ballistic missile launch from a strategic submarine fully achieved the latest military, scientific and technical requirements.”

North Korea is under United Nations sanctions banning it from developing or using ballistic missile technology.

The United States would not comment on the reported test but said launches using ballistic missile technology were a “clear violation” of UN Security Council resolutions.

“We call on North Korea to refrain from actions that further raise tensions in the region and focus instead on taking concrete steps toward fulfilling its international commitments and obligations,” a State Department official said in an e-mail.

The KCNA report did not mention the date or the exact location of the test, but a separate KCNA dispatch yesterday said Kim gave field guidance at a fishery complex in Sinpo, a port city on the country’s east coast and the location of a known submarine base.

The test, if verified, would mean North Korea can move its missiles within range of the US, said Korea analyst Victor Cha of the Centre for Strategic and International Studies in Washington.

“The test shows that North Korea missile capabilities are advancing without any constraints now despite a bevy of nonproliferation sanctions applied by the United Nations,” he said in an e-mail.