North Korea on Saturday warned it was prepared to use nuclear weapons if it was invaded by the United States and South Korea.

The official Korean Central News Agency (KCNA) carried the remarks by the North's Joint Chief, General Ri Yong-Ho, during a national meeting on the eve of the birthday of the communist country's armed forces.

"The revolutionary armed forces of the DPRK (North Korea) are fully ready to frustrate any provocation of the aggressors at a single blow," Ri said.

"They will mobilise all means including the nuclear deterrent... should the US imperialists and the south Korean puppet warmongers dare intrude into the inviolable sky, land and seas of the DPRK even 0.001mm," he said.

He added that "a grave situation is now prevailing on the Korean Peninsula" because of the neighbouring South and its ally the United States, who he said wanted to start a war.

The harsh rhetoric comes as tensions between the two Koreas are high over the sinking of a South Korean warship last month near the disputed sea border in the Yellow Sea with a loss of 46 lives.

Seoul has been careful not to point the finger directly at the North over the incident in the Yellow Sea, which has stoked already tense ties, and Pyongyang has denied it was to blame.

The tensions prompted US Secretary of State Hillary Clinton to say she hoped there would be "no miscalculation" that could spark a new war between the Koreas.

earlier related report
Seoul believes N.Korea torpedoed navy ship: report
Seoul (AFP) April 22, 2010 - South Korea's military believes that a North Korean submarine launched a torpedo attack to sink a South Korean warship last month near their disputed sea border, the Yonhap news agency said Thursday.

The assessment was reported to the office of President Lee Myung-Bak and the defence ministry immediately after the ship sank last month, an unnamed senior military source told Yonhap.

"It's our military intelligence's assessment that North Korean submarines attacked the ship with a heavy torpedo," the source said, adding that the subs were armed with torpedoes with 200-kilogram (440-pound) warheads.

"Since February last year, North Korea has strengthened training that showed the possibility of it launching a guerrilla warfare-style provocation, rather than a skirmish."

The South's military intelligence command had also alerted the navy ahead of the March 26 sinking of the Cheonan that North Korea was preparing an attack, Yonhap said.

The South's defence ministry refused to comment on the report.

Seoul has so far refrained from directly accusing Pyongyang and said only that an "external explosion" was the most likely cause of the disaster which cost the lives of 46 sailors.

Pyongyang has denied it was responsible.

South Korean Defence Minister Kim Tae-Young has already raised the possibility that a mine or torpedo may have sunk the ship, following deadly naval clashes in 1999 and 2002 and a November firefight.

The November incident left a North Korean patrol boat in flames and local media reports said one North Korean sailor was killed and three wounded.

The North has vowed "merciless" military action to protect what it sees as its Yellow Sea border.

South Korea's Chosun Ilbo newspaper meanwhile quoted defectors as saying that North Korea had formed suicide attack squads known as "human torpedoes" in its navy.

It said the North's navy operates a brigade of suicide attack squads, which have many mini-submarines capable of carrying torpedoes or floating mines.

S.Korea, China to hold summit in Shanghai
Seoul (AFP) April 25, 2010 - South Korean President Lee Myung-Bak and China's President Hu Jintao will hold a summit on the sidelines of Shanghai's World Expo, officials said Sunday, amid tensions on the Korean peninsula.

The two will discuss ways to enhance their strategic partnership and "political situations in the region," at the meeting Friday, on the eve of the expo's opening, Lee's office said.

Lee will stay in Shanghai for two days until Saturday, it added.

Tensions have been raised on the Korean peninsula after a 12,000-tonne South Korean warship sank following a mysterious explosion on March 26, leaving 46 sailors dead or missing.

Seoul's defence chief Sunday cited a torpedo attack as one of the "most likely" causes of the sinking near the South's disputed border with North Korea. The North has denied involvement.

Lee has vowed a "resolute" response to the disaster, describing the worst peacetime loss of life for South Korea's navy as a "wake-up call" and calling the North the world's "most belligerent" state.

The two Koreas are technically at war after an armistice ended fighting in their 1950-1953 conflict.

The Yellow Sea border was the scene of deadly naval clashes between the North and South in 1999 and 2002 and a firefight last November that left a North Korean patrol boat in flames.

Lee has taken a tough stance toward Pyongyang, while the North's nuclear weapons development sparked international condemnation and sanctions.

China, a traditional ally of North Korea, has been expanding political exchanges and economic cooperation with South Korea after establishing diplomatic relations with Seoul in 1992.

China, however, has sided with neither North nor South whenever sensitive political and diplomatic issues are raised between the two Koreas.

China has been hosting six-party nuclear disarmament talks on North Korea since 2003 but the multilateral diplomatic process -- which also groups the two Koreas, the US, Japan and Russia -- has been stalled.

The North quit the process in April 2009, a month before it conducted a second nuclear test.