But the presence of missiles themselves and their launch pads have not been confirmed, the major daily Yomiuri Shimbun said, quoting Japanese and US government sources.

"The chances of an actual Rodong missile launch are slim. We can't rule out the possibility that the activity was just a large-scale military drill," the daily quoted one senior official as saying.

On Thursday, South Korean military officials said data collected jointly with US satellites and spy planes suggested North Korea might be preparing to test-fire a missile.

Missile and other units of North Korea's three services have been acting on orders mainly coming from a Rodong missile base in Sinori, northwest of Pyongyang, Yomiuri quoted the sources as saying.

A Rodong missile, with a range of some 1,300 kilometers (810 miles), can hit most areas in Japan.

Near these bases, vehicles carrying liquid missile fuel, other military vehicles, military personnel and missile engineers were seen gathering, the sources said.

The data have been collected by US and Japanese spy satellites and radio monitors and electronic surveillance aircraft, Yomiuri said.

But another Japanese daily Sankei Shimbun reported Sunday that North Korea might be preparing to fire a longer-range missile, called Rodong-B or R-27 by Western experts, which can carry a nuclear warhead.

This missile, a modified version of the former Soviet submarine-launched SSN-6 ballistic missile, has a range of up to 3,600 kilometers (2,250 miles) and can hit the US military base on the Pacific island of Guam, the daily said.

Sankei quoted US government sources as saying there had been "no evidence" to suggest the actual launch of a missile and that Pyongyang's moves could have been a "diplomatic, strategic ploy" to unnerve Washington or Tokyo.

North Korea stunned the world in August 1998 by test-launching over Japan a Taepodong-1 missile with a range of up to 2,000 kilometers (1,250 miles), claiming it was a satellite launch.

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