SEOUL: A North Korean military think tank on Monday dismissed South Korea's recently tested submarine-launched ballistic missile as clumsy and rudimentary but warned its development would rekindle cross-border tension.

Both South and North Korea, which have been developing increasingly sophisticated weapons amid stalled efforts to ease tension on the peninsula, tested ballistic missiles on Wednesday.

Jang Chang Ha, chief of the Academy of the National Defence Science, a North Korean state-run weapons development and procurement centre, said in a commentary on the official KCNA news agency that media photographs of the latest South Korean missile showed a "sloppy" weapon that did not even have the shape of a submarine-launched ballistic missile (SLBM).

The missile seemed to be a version of the South's Hyunmoo surface-to-surface ballistic missiles with the warhead part an imitation of India's K-15 SLBM, Jang said.

The photographs of the test indicated that South Korea had yet to achieve key technologies for the underwater launch including complicated fluid flow analysis, he said.

"In a word, it should be called some clumsy work," Jang said. "If it's indeed an SLBM, it would only be in its rudimentary, infant stage."

South Korea's defence ministry did not immediately respond to a request for comment.

Jang said the weapon had not reached a phase where it had strategic and tactical value and would thus pose a threat to the North but questioned the intent of the South's ongoing missile development.

"The South's enthusiastic efforts to improve submarine weapons systems clearly presage intensified military tension on the Korean peninsula," Jang said. "And at the same time, it awakens us again and makes us sure of what we ought to do."

Jang's comments came days after Kim Yo Jong, the powerful sister of North Korean leader Kim Jong Un, derided the South for criticising the North for what she said were "routine defensive measures" while developing its own missiles.

North Korea has been steadily developing its weapons systems, raising the stakes for talks aimed at dismantling its nuclear and ballistic missile arsenals in return for U.S. sanctions relief.

The negotiations, initiated between Kim Jong Un and former U.S. President Donald Trump in 2018, have stalled since 2019.