North Korea launched a Musudan intermediate-range ballistic missile early Tuesday morning, but the launch ended in failure, South Korea's Joint Chiefs of Staff and military sources said.

"North Korea attempted to launch an unidentified missile from Wonsan, Gangwon Province, at around 5:20 a.m., but it is presumed to have been unsuccessful," the JCS said in a brief text message.

The military is studying the details of the launch and is maintaining a high level of combat preparedness, the JCS said.

Official sources said the launched missile was a Musudan intermediate-range ballistic missile.

The sources said the missile may have exploded on the mobile launcher immediately after the fire button was pushed. They said the explosion is presumed to have inflicted serious injuries on personnel in the immediate vicinity.

JCS spokesman Jeon Ha-kyu said in a press briefing that North Korea seems to be pushing for a continued string of ballistic missile launches following leader Kim Jong-un's orders for such tests to be carried out on March 15.

"The military is keeping open the possibility that the North will conduct additional provocations," he said.

The latest launch marks Pyongyang's fourth failed attempt to launch its Musudan mid-range ballistic missiles in two months.

On April 15, North Korea launched its first Musudan missile as the country was gearing up for a high-profile ruling party congress in early May. But the launch ended in failure, dealing a humiliating blow to North Korea.

This was followed by Pyongyang firing off two more of the same IRBMs in a single day on April 28, although both of these launches failed too.

North Korea has deployed about 50 Musudan missiles with its forces since 2007, but none of them had been test-fired until this year.

The back-to-back launch failures stoked skepticism on the reliability of North Korea's Musudan missiles.

Military officials had predicted for some time that North Korea would carry out additional ballistic missile launches or a nuclear detonation test to make up for its unsuccessful launch attempts in April.

A day earlier, the JCS said it was closely tracking signs of a possible ballistic missile launch by North Korea following Japanese media reports on North Korea's launch preparations. (Yonhap)