North Korea fired what appeared to be an intermediate-range ballistic missile on Thursday but it crashed seconds after the test launch, South Korea's defence ministry said.
North Korean officials did not immediately comment.
Al Jazeera's Harry Fawcett, reporting from Seoul, said the South Korean defence ministry claimed the missile was fired at 6:40am local time.
A defence ministry official told the Reuters news agency that it appeared to be a Musudan missile with a range of more than 3,000km - the same type of rocket believed to have failed in a test launch earlier this month.
The powerful mid-range missile could one day be capable of reaching far-off US military bases in Asia and the Pacific. It exploded in the air a few seconds after it launched, the Southern official said.
"We are also hearing from the semi-official Yonhap news agency, citing unnamed military officials, that it was not detected on the South Korean military radar system because it apparently did not get high enough to be detected by that system," Fawcett said.
He added, though, that it was detected by a US intelligence satellite over North Korea.
The apparent launch came as the Koreas traded threats as Pyongyang expressed anger over annual South Korean-US military drills that the North calls a rehearsal for an invasion.
Last week, North Korean leader Kim Jong-un hailed a submarine-launched ballistic missile test as an "eye-opening success", declaring that Pyongyang had the ability to strike Seoul and the United States whenever it pleases.
The reported crash comes ahead of a major ruling party meeting next week in Pyongyang.
"It is a very rare event," Fawcett said. "It is the seventh such event since the foundation of the ruling party of North Korea. It is very much centred around the personage of Kim Jong-un and his general status."
Source: Al Jazeera and agencies