US satellites have picked up signs that North Korea is preparing to launch a long-range missile, a Japanese newspaper reported on Friday.

North Korea moved missile parts from its military factory in Pyongyang to a launch pad in Tongchang-ri in the country's far northwest early November, the Asahi Shimbun said.

The US government has already informed its counterparts in Japan and South Korea about the move, the daily said, adding that the three countries had increased vigilance.

The developments came after North Ko1rea carried out a failed rocket launch in April in what the communist state said was an attempt to put a satellite into orbit from the same launch pad.

According to the daily, images of the shipment recently taken by US satellites were similar to one used in the April launch.

Pyongyang is technically ready to launch a missile late November, but an immediate launch is unlikely ahead of South Korea's presidential election next month, the Asahi said.

North Korea has not announced any plans to launch a rocket.

Immediate confirmation by the Japanese government was not available.

In Seoul, a South Korean defence ministry spokesman said it could comment on any matter of intelligence, while a presidential Blue House spokeswoman said she had no information.

N. Korea threatens repeat of island shelling
Yeonpyeong, South Korea (AFP) Nov 22, 2012 - North Korea has threatened to repeat its 2010 artillery attack on a border island, as South Korea prepares to mark on Friday the second anniversary of the shelling that left four dead.

The South plans to hold several commemorative events over the next few days on Yeonpyeong island near the disputed Yellow Sea border and will conduct a military drill in the area on Friday.

North Korea heaped scorn on the memorial activities, with the official Korean Central News Agency (KCNA) on Thursday quoting a military spokesman who warned of another attack on the island.

"The commemoration... on Yeonpyeong Island will lead to the second Yeonpyeong Island disaster," the spokesman said.

The November 23, 2010 shelling of the island killed two South Korean marines and two civilians in one of the most serious border incidents since the 1950-1953 Korean War.

The North said the attack was in response to a live-fire drill by the South, which, it claimed, had resulted in shells falling on its side of the sea border.

South Korean troops responded with cannon fire and the government met in an underground war room, fuelling fears that the situation could escalate into a full-scale conflict.

The de facto maritime boundary between the two Koreas -- the Northern Limit Line -- is not recognised by Pyongyang, which argues it was unilaterally drawn by the US-led United Nations forces after the war.

The North Korean spokesman said the South's plans to commemorate the anniversary of the shelling were a "ridiculous farce" that invited derision and censure.

The only regret on the North's side, he said, was that the military had not seized the opportunity two years ago "to send the whole of Yeonpyeong Island to the bottom of the sea.

"It is the steadfast will of the service personnel not to miss the opportunity to do so if the warmongers perpetrate another provocation," he added.

South Korea has stressed that Friday's military drill will not include any live-fire exercises.

Since the Yeonpyeong shelling, South Korea has upgraded its defences on frontline islands in the area.

Yeonpyeong's 1,200 residents, who live just 1.5 kilometres (one mile) from the disputed border, are now outnumbered by the marines posted there.

Last month, President Lee Myung-Bak paid a surprise visit to the island and spoke to the troops about the need to defend the maritime border "to the last man".

On a tour later Thursday of an army command post south of Seoul, Defence Minister Kim Kwan-Jin underlined concerns that Pyongyang might seek to trigger a confrontation ahead of the South's presidential election on December 19.

"North Korea could commit provocative acts in order to inject fears of war into South Koreans before the election," Kim said.

"After the election, it may provoke the South to test the new government and tame it," he said, adding that when "gangsters" attack the only way to respond was with "a large club".