North Korea assembling long-range missile: report

North Korea appears to have begun assembling a missile believed capable of striking US soil, a report said as tensions rose along the heavily fortified border with the South.

The communist regime of ailing North Korean leader Kim Jong-Il has defied international criticism of its second nuclear test by firing a volley of short-range missiles and threatening to attack the capitalist South.

It is now said to be preparing to test-launch an intercontinental ballistic missile as well as several medium-range missiles.

The North is believed to have started putting together a long-range missile that may be a modified version of the Taepodong-2 which it fired over Japan in April, South Korea's JoongAng Ilbo daily reported Wednesday.

Although the missile is being kept under covers, "the length of its propulsion rocket seems to be longer than the last one fired in April although its shape looks similar," it quoted a government source as saying.

The North said its last long-range rocket launch on April 5 was to put a satellite into orbit.

The United States and its allies said it was really a test of the Taepodong-2, which could theoretically reach Alaska at maximum range.

"After carrying out a missile test, it usually takes at least six months to adjust defects and prepare to fire another one," said an unnamed military official quoted by the JoongAng Ilbo.

"Now, the North is preparing to do it again after just two months. It seems the North is in quite a hurry."

Analysts believe Kim is trying to bolster his authority so he can put in place a succession plan reportedly involving his third son, 26-year-old Kim Jong-Un.

South Korean and US forces on the peninsula are on heightened alert after the North warned of a possible attack in response to Seoul's decision to join a US-led initiative to stop the spread of weapons of mass destruction.

The situation is tense along the heavily militarised inter-Korean border -- the world's last Cold War frontier -- where North and South Korean troops eye each other warily from either side of the demarcation line.

In the village of Panmunjom inside the Joint Security Area, where the truce that ended the Korean War was signed in 1953, visitors from the South were told Wednesday to do nothing that might provoke the North Koreans.

"The possibility of armed provocation from the northern side is higher than ever in the Joint Security Area," said Corporal Yoo Hyun-Woo. "So please do not point or make any gestures toward the North Koreans."

The North is also reported to have stepped up naval drills near the western sea border, the site of deadly skirmishes between the two Koreas in 1999 and 2002.

South Korea Tuesday sent a high-speed navy patrol boat armed with guided missiles to the area and vowed to "punish" any attacking forces.

US Deputy Secretary of State James Steinberg met South Korean officials Wednesday to discuss ways to take North Korea to task for its nuclear test.

Washington and Seoul "share the same assessment of the dangers that we face by the developments in North Korea's missile and nuclear programmes," he said.

Steinberg arrived from Japan and will go on to China, which hosts six-party talks on North Korea's nuclear disarmament. The talks also include the two Koreas, Japan, the US and Russia.

After the UN Security Council censured its April 5 rocket launch, the North announced it was quitting the talks and restarting a programme to make weapons-grade plutonium.

On May 25 it tested a nuclear bomb several times more powerful than the one detonated in 2006.

The US envoy for North Korea, Stephen Bosworth, said he was hopeful Pyongyang would eventually return to negotiations.

"I think it's important for the five parties to make sure that we do everything possible to keep the prospects for the dialogue alive. And I have some confidence that at some point we're going to see it resume," Bosworth, who was travelling with Steinberg, told his South Korean counterpart Wednesday.

Amid the growing tensions, two female American journalists will go on trial in North Korea's highest court Thursday on charges that could send them to a labour camp.

Euna Lee and Laura Ling were detained by North Korean border guards in March along the narrow Tumen River which marks the border with China, while researching a story about refugees fleeing the hardline communist state.