SEOUL - SOUTH Korea's defence chief said on Tuesday that North Korea appeared to be pushing forward with a uranium enrichment programme, stoking fears the secretive communist state may use it for nuclear weapons.

'It appears to be clear that North Korea is pushing ahead with (uranium enrichment),' Defence Minister Lee Sang Hee told parliament.

Regional tension spiked after North Korea on May 25 carried out its second nuclear test, followed by missile launches, which resulted in new UN sanctions.

The North has also vowed to build more nuclear bombs and to start a new weapons programme based on uranium enrichment.

Mr Lee said the enrichment process was easier for North Korea to hide than reprocessing its plutonium stockpiles for atomic warheads because 'it can be done in a space as small as 600 sq m'.

US claims in 2002 that Pyongyang was running a secret uranium enrichment programme, in addition to its admitted plutonium-based operation, led to the collapse of a nuclear disarmament deal.

On Tuesday North Korea renewed its confrontational rhetoric, threatening to bolster its nuclear deterrence against the United States, amid suspicions that it is preparing to fire more missiles.

The cabinet newspaper Minju Joson said North Korea would go ahead with an 'open nuclear confrontation' with the United States, citing a 'grave' situation.

North Korea 'will strengthen its self-defensive nuclear deterrent to safeguard its sovereignty and safety,' the paper said in a commentary.

The North's policy has grown notably harder-line this year, after leader Kim Jong Il was widely believed to have suffered a stroke last August.

US and South Korean officials believe the ailing Mr Kim is projecting an image of strength to bolster his authority as he prepares one of his sons for a takeover. -- AFP