North Korea did not test fire a ballistic missile from a submarine as Pyongyang claimed over the weekend and the country is still a long way from achieving such a capability, US officials said Monday.

The North's state media said on Saturday that a new submarine-launched ballistic missile (SLBM) had been tested but US officials rejected the regime's account.

"That was not a ballistic missile," a defense official told AFP.

The official played down the test, saying it did not represent a technical breakthrough for the North.

"They are trying to develop that capability," but there was no "imminent" threat of a submarine-launched missile arsenal coming on line in North Korea, said the official, who spoke on condition of anonymity.

Pyongyang's state media said North Korean leader Kim Jong-Un touted the test as an "eye-opening success" that gives his military a "world-level strategic weapon."

The precise nature of the launch remained unclear. Some analysts suggested the missile might have travelled only a few hundred meters, and that the event did not qualify as a full flight test.

South Korea called on North Korea to halt the program and assessed Pyongyang was still in the "early phase" of developing submarine-launched missiles.

But a defense official in Seoul, speaking on condition of anonymity, said the North could have a fully operational submarine armed with ballistic missiles within four or five years.

Experts say North Korea bought submarine missile technology from Russia shortly after the end of the Cold War, and has tried to reverse-engineer old Russian subs to build a launch system.

"We don't expect them to develop a highly capable system anywhere remotely similar to our ballistic missiles on submarines, but if they can put a missile on a submarine, even a short to medium-range missile, then that would obviously complicate our effort to track their missiles," John Schilling, an aerospace technology expert, said at a conference in Washington last week.

North Korea is still years away from building long-range missiles that could be fired from subs, according to a recent report by Schilling, who used to advise the US Air Force and now works for the Aerospace Corporation.

The Pentagon declined to comment on the test, saying the US government could not discuss "intelligence matters."

"Any type of launch of this nature would violate at least four UN Security Council resolutions. And it's another example of North Korea's unwillingness to play by the international rules," spokesman Colonel Steven Warren said.