SEOUL (South Korea) - THE decision on who will become North Korea's next leader may not be final despite reports that Kim Jong Il has tapped his youngest son to succeed him, South Korea's defence chief said.

Who will take over as ruler of nuclear-armed North Korea after Mr Kim has been the focus of intense speculation since the 67-year-old reportedly suffered a stroke last August.

South Korea's spy agency told lawmakers that Pyongyang notified its diplomatic missions and government agencies overseas that 26-year-old Kim Jong Un, the youngest of Mr Kim's three sons, will inherit the leadership of the communist nation.

But Defence Minister Lee Sang-hee told the National Assembly on Tuesday that intelligence suggests a final decision has not been made. He did not elaborate.

His comments added to the murky succession drama in the reclusive country. The conflicting assessments come amid tensions over the North's May 25 nuclear test and signs that the regime is preparing to test-fire missiles in violation of UN Security Council resolutions.

Pyongyang has issued a no-sail zone through July 10 in waters off its east coast for 'military drills'. Kim Jong Il has controlled the impoverished nation of 24 million with absolute authority since his father's death in 1994. Regional powers fear instability and a power struggle if he dies without naming a successor. North Korea has denied Mr Kim was ever ill, but he appeared gaunt in an April appearance at parliament.

Mr Lee told lawmakers that South Korea's military was keeping a close watch on Mr Kim's health amid possible signs his condition has worsened.

Mr Lee also said it's clear that the North - which conducted two underground nuclear tests in 2006 and in May this year - was pursuing an uranium enrichment program, which can be more easily hidden than a plutonium-producing reactor.

Meanwhile, a US delegation headed by Philip Goldberg left Tuesday for Beijing to discuss UN sanctions slapped on North Korea for a nuclear test last month, the State Department said. Goldberg, a former ambassador, is in charge of coordinating the sanctions' implementation.

China's cooperation in enforcing sanctions against its neighbour is seen as crucial to increasing pressure meant to push the North back to nuclear disarmament talks. -- AP