Pyongyang's announcement last week that it possessed nuclear bombs came as no surpise to Washington which has for years believed that North Korea has developed one or two crude nuclear devices.

South Korea's National Intelligence Service (NIS) said in a report to parliament that North Korea's claim could be true.

But North Korea's nuclear technology falls short of allowing it to launch a nuclear missile, Yonhap news agency quoted the confidential report as saying.

"North Korea might have developed one or two conventional nuclear bombs, but if it did, it may not have the technology to launch them on missile," the NIS report said, according to Yonhap.

The intelligence agency dismissed an earlier claim by Pakistan's disgraced nuclear scientist Abdul Qadeer Khan that he witnessed a North Korean missile carrying a nuclear warhead during his visit to the Stalinist country.

"We believe North Korea has not acquired enough technology to miniaturize nuclear bombs which must weigh less than 500 kilograms to be mounted on missile," the report said.

North Korea has a well-advanced missile programme and among Washington's greatest fears is that Pyongyang will achieve the technical goal of marrying its ballistic missile development with its pursuit of nuclear weapons.

Former CIA Director George Tenet said two years ago he suspected that North Korea was perfecting a missile that could deliver a nuclear bomb to most parts of the continental United States.

Vice Admiral Lowell Jacoby, director of the Defense Intelligence Agency, also said at that time that the Taepodong-2 missile could target parts of the US with a nuclear weapon-sized payload in the two-stage configuration, and has the range to target all of North America if a third stage was used.

The reclusive country is reportedly developing Taepodong-2 with a range of 6,700 kilometers (4,150 miles).

Pyongyang stunned the world in 1998 by test-launching over Japan a Taepodong-1 missile with a range of up to 2,500 kilometers.

It also has short-range Scud-Bs with a range of 300 kilometers as well as Scud-Cs with a range of 500 kilometers, targetting South Korea.

According to a news report Tuesday, Pyongyang has recently deployed a new "Scud-ER" with a 1,000 kilometer range.

It also has intermediate-range Rodong missiles with a 1,300 kilometer range which can hit targets in most areas of Japan.

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