By Jon Herskovitz
SEOUL (Reuters) - North Korea appears to be enriching uranium, potentially giving the state that has twice tested a plutonium-based nuclear device another path to making atomic weapons, South Korea's defence minister said on Tuesday.
"It is clear that they are moving forward with it," Defence Minister Lee Sang-hee told a parliamentary hearing, adding such a programme was far easier to hide than the North's current plutonium-based activities.
North Korea earlier this month responded to U.N. punishment for its most recent nuclear test in May by saying it would start enriching uranium for a light-water reactor.
Experts said destitute North Korea lacks the technology and resources to build such a costly civilian reactor but may use the programme as a cover to enrich uranium for weapons.
North Korea, which has ample supplies of natural uranium, would be able to conduct an enrichment programme in underground or undisclosed facilities and away from the prying eyes of U.S. spy satellites.
The North's plutonium programme uses an ageing reactor and is centred at its Soviet-era Yongbyon nuclear plant, which has been watched by U.S. aerial reconnaissance for years.
Proliferation experts said the North has purchased equipment needed for uranium enrichment, including centrifuges and high-strength aluminium tubes, but they doubt that Pyongyang has seriously pursued the project.
"It seems unlikely that North Korea will succeed in establishing a substantial enrichment capability ... in the near term," nuclear expert Hui Zhang wrote in an article this month in the Bulletin of the Atomic Scientists, adding outside help from the likes of Pyongyang's ally Iran could speed up the process.
A U.S. accusation that Pyongyang was clandestinely operating a uranium enrichment plan led to the breakdown of a 1994 disarmament deal. New, six-way nuclear talks began in 2003 but are now dormant after the North quit the process in April.
MILITARY MOVES
South Korean officials said the North's recent military moves, which also included missile tests and threats to attack the South, were likely aimed at building internal support for leader Kim Jong-il, 67, as he prepares the ground for his youngest son to take over Asia's only communist dynasty.
Japanese Prime Minister Taro Aso said on Tuesday it was necessary to put "strong pressure" on North Korea.
"We need to show (North Korea) that it would not benefit from any further act of provocation. On the other hand, we have not closed our door to resolving issues through talks," Aso said in a speech in Tokyo.
The U.S. point man for sanctions on North Korea aimed to stamp out its arms sales, one of the few sources of hard currency for the cash-short North, will arrive in Beijing on Thursday for discussion, a Chinese Foreign Ministry spokesman said.
Spokesman Qin Gang also told a briefing there was no basis to reports in Japan's Asahi newspaper and Financial Times that Kim's son Jong-un had visited Beijing as a way of informing the North's biggest benefactor that he is the heir apparent.
Investors used to the North's military rumblings said the developments have not had any major impact on trading but have raised concern among market players.
North Korea is also preparing to test a long-range missile that could hit U.S. territory and mid-range missiles that could hit all of South Korea, which could further rattle regional security, a South Korean presidential Blue House official said last week.
A North Korean fishing boat briefly entered South Korean waters off the west coast on Tuesday afternoon, but was retrieved without a clash, Seoul's Yonhap News agency reported.
As the fishing boat with a broken engine drifted south in heavy fog, a South Korean military vessel notified the North of the incident. North Korea did not respond initially but its guard ship later tugged the boat north, Yonhap said.
Some analysts have speculated the North could push tensions further by engineering a naval clash on the disputed sea border.
(Additional reporting by Christine Kim and Rhee So-eui in SEOUL, Ben Blanchard in BEIJING and Yoko Nishikawa in TOKYO; Editing by Sanjeev Miglani and Alex Richardson)
