North Korea threatened military action Tuesday in response to any UN censure over the sinking of a South Korean warship, triggering a US rebuke and ratcheting up tensions in the volatile Korean peninsula.

"We don't want the Security Council to take measures provoking us," Pyongyang's ambassador to the United Nations, Sin Son Ho, told reporters in a rare press conference here by North Korea.

If the 15-member UN Security Council takes action against Pyongyang "follow-up measures will be carried out by our military forces...I (will) lose my job," he warned.

In Washington, State department spokesman Philip Crowley slammed what he called yet another example of Pyongyang's "provocative behavior."

Sin also insisted that North Korean investigators be allowed to visit the site where the South Korean corvette, the Cheonan, was sunk by a torpedo on March 26, killing 46 sailors.

"If South Korea has nothing to hide, there is no reason for them not to accept our inspection group," he said.

Tensions surged on the Korean peninsula after a multinational investigation said last month a submarine from the North torpedoed the 1,200-tonne Cheonan near the disputed Yellow Sea border.

Pyongyang has angrily denied any responsibility and on Saturday the general staff of the Korean People's Army said it would attack loudspeakers set up by Seoul to broadcast cross-border propaganda.

A South Korean envoy Monday urged the Security Council to take action against the North after giving evidence about the incident.

"We identified the torpedo as a North Korean CHT02D on the basis of our recovered pieces of the torpedo," said Yoon Duk-Yong, a physics and material science expert at the Korea Advanced Institute of Science and Technology.

The Security Council has called on South and North Korea "to refrain from any act that could escalate tension in the region" and to preserve peace and stability on the peninsula.

But the North Korean envoy Tuesday dismissed the South Korean version as "fabrication."

He even quipped that a North Korean torpedo may also be blamed for last week's failure of a South Korean rocket launch.

The Naro-1 rocket, which was Russian-made but assembled in South Korea, veered off course and exploded 137 seconds after blast-off last Thursday.

"We need to dispatch our own investigative group to the site of the sinking," Sin said, accusing the United States of fomenting the tensions.

"If the Security Council formally debates this case with only the unilateral 'investigation result' of the South but without verification by the DPRK (North Korea), the victim, it will mean that the Security Council takes the side of one party of dispute excluding the other," he added.

Pyongyang's envoy noted that at the time of the sinking, joint US-South Korean military exercises "Foal Eagle" were in full swing with the deployment of an array of anti-submarine and anti-air assets.

"Amid these conditions, it is doubtful that a DPRK (North Korea) small-size submarine attacked the corvette 'Cheonan,' which has anti-submarine capacity," he said.

"It is also inconceivable that the US and South Korean warships equipped with state-of-the-art devices failed to detect the submarine," Sin said.

The envoy also wondered why the survivors "were ordered to keep silent about the sinking" and why the South Korean military did not release "the records of sailing and communications and visual records of the time of the incident."

Washington mostly benefited from the incident, he alleged, saying the United States "hyped the threat from North Korea" to force Japan's ruling Democratic Party to give up plans to drive US forces out of a base in Okinawa.

He accused the United States of using the incident to "re-accelerate the formation of the tripartite alliance keeping hold on Japan and South Korea as its servants."

Washington was seeking "to strike a deal of massive arms trade with South Korea and to dispatch US aircraft carriers to the West Sea of Korea, which is a delicate area in terms of security of the Korean peninsula and China," Sin said.

The two Koreas have remained technically at war since the end of the 1950-53 conflict, which was ended only by an armistice.