A South Korean intelligence paper says North Korea has deployed new missiles to hit more parts of Asia and increased its special warfare troops.

The defence White Paper says the North has deployed a new mid-range missile that can travel up to 3,000 kilometres and hit all of Japan.

Recently American and South Korean intelligence agencies warned that the communist North is preparing to test its longest-range missile, which is capable of reaching US territory.

The biannual paper says the North has increased the number of its special warfare soldiers by 60,000 while modernising its infantry forces to better attack the south.

It said the overall size of the military had grown by 20,000 to 1.19 million since 2006, but the number of lightly equipped special forces trained swiftly to infiltrate South Korea had increased 50 per cent to 180,000.

"After examining the wars in Iraq and Afghanistan, North Korea appears to have developed new strategies that can complement its shortfalls while reinforcing its strengths," said Shin Won-Sik, deputy for policy planning at the defence ministry.

"Their aim appears to blur the line between friend and foe once a conflict erupts," Yonhap news agency quoted him as saying, suggesting the North would wage guerrilla warfare to compensate for a lack of advanced weaponry.

"North Korea deems it very important to be able to quickly cause disarray among its enemies," Mr Shin told a briefing.

Brink of war

But North Korea today accused South Korean President Lee Myung-Bak of bringing the peninsula "to the brink of war".

"The Lee group has pushed the inter-Korean relations to the phase of total collapse and driven the situation to the brink of a war during the first year of its office," said Rodong Sinmun.

Mr Lee, 67, who was sworn in on February 25, 2008, promised massive economic aid to the north - but only if it fully denuclearised.

Pyongyang has since halted all talks with Seoul, calling Mr Lee a "traitor" and "despicable human scum".

Last week the North's military announced that it was "fully ready" for war with the south.

South Korean unification minister Hyun In-Taek has denied that Seoul is to blame for strained cross-border relations.

"The south's policy on North Korea is not the cause of the chill in relations," he said in a report to the ruling Grand National Party.

"The cause is the North's hardline position towards the South."

A substantial threat

US and South Korean officials have also said the North is preparing to test-fire its longest-range missile, the Taepodong-2, which has an estimated range of 6,700km.

"North Korea is a substantial, not symbolic, threat to us (South Korea)," said Baek Seung-Joo of the Korea Institute for Defence Analyses.

"The special warfare forces, if combined with North Korea's chemical weapons, could not only inflict substantial damage on us but also drive South Korea into panic quickly," he said.

US secretary of state Hillary Clinton warned the North to stop provocation and said its war of words with the South would not help it forge a new relationship with Washington.

She said any missile test would breach a United Nations resolution and urged Pyongyang to comply with a six-nation nuclear disarmament pact.

- AFP/Reuters