North Korea's failed launch of its Musudan intermediate-range ballistic missile last week sparked a huge fireball that damaged the launcher and could have also injured or killed missile technicians on the ground, a news report said Wednesday.

The missile blew up about 300 feet above the ground, shortly after Friday's launch, and U.S. strategic defense surveillance systems, both airborne and space-based, videotaped the explosion, the Washington Free Beacon reported, citing U.S. defense officials.

Two road-mobile Musudan launchers were set up for the test, but the second was not fired after the explosion, the report said. It also cited a diplomatic source as saying that the likely cause of the explosion was a faulty fuel system or turbo pump failure.

The Musudan intermediate-range ballistic missile is an indigenous variant of the Russian SS-N-6 submarine-launched ballistic missile, known by Moscow as the R-27, which the North obtained covertly from Russia sometime in the 1990s, the report said.

"The North Koreans seemed to just believe it would succeed because the R-27 SLBM of former Soviet Union was one of the most tested nuclear warhead delivery systems ever produced, and North Korea had already done a lot of ground tests," the source was quoted as saying. "However, a real launching test is totally different from the ground test."

Western intelligence agencies do not know the ultimate cause of the launch failure. "And the North Koreans probably don't either," the source said, according to the report.

Comment from the U.S. Defense Department was not immediately available.

The launch was the latest in a series of provocative acts the North has undertaken in defiance of international pressure increased in the wake of its fourth nuclear test in January and a long-range rocket launch the following month.

Concerns also persist that Pyongyang could carry out yet another nuclear test in an effort to project an image of Kim Jong-un as a strong leader in the lead-up to the Workers' Party Congress next month. (Yonhap)