North Korea has set up an independent military division to deploy and operate its medium-range ballistic missiles, a report said Tuesday.

A South Korean government source quoted by Yonhap news agency said the move indicates the North's determination to continue developing IRBMs (intermediate-range ballistic missiles).

With a range of more than 3,000 kilometres (1,860 miles), these are capable of hitting US military bases in Japan and Guam.

North Korea has defied a UN Security Council resolution ordering it to halt work on its ballistic missile programme.

"We believe the operation of this separate unit indicates North Korea's intention to produce new IRBMs," the source was quoted as saying. "These missiles have US military bases in Japan and also in Guam in range."

Seoul's 2008 defence ministry white paper confirmed the North recently deployed intermediate-range missiles after developing them since the late 1990s, but gave no details.

"We presume that it is natural for the North to have a unit to run the weaponry system, but we cannot confirm whether such a division has been created," ministry spokesman Won Tae-Jae told a briefing.

North Korea has developed a missile called the Musudan-1 with a range of 3,000 km, in addition to its intercontinental Taepodong missiles, experts say.