North Korea has been developing a uranium enrichment programme -- a potential second way to make nuclear bombs -- since the late 1990s, a senior defector was Wednesday quoted as saying.

The defector, quoted by South Korea's Chosun Ilbo newspaper, said centrifuges for the programme are being made at the city of Heechon, 57 kilometres (35 miles) northeast of its main nuclear complex at Yongbyon.

The North heightened security fears in November when it showed off an apparently functioning uranium enrichment plant, said to be equipped with thousands of centrifuges, to visiting US scientists.

It says the project is part of a peaceful energy programme. But experts say it could easily be reconfigured to produce weapons-grade uranium, giving it a second way to make a bomb in addition to an acknowledged plutonium operation.

The defector was described by Chosun as a former senior government official in the North with deep knowledge of military industries.

The defector reportedly said the work at Heechon began in the late 1990s -- about a decade before the North publicly announced it was pursuing uranium enrichment.

"Motors -- a main component of the centrifuges -- were imported from countries like Japan, France and Russia since the North couldn't make them on its own," the paper quoted the former official as saying.

Heechon is home to many precision machinery plants and electrical component factories, Chosun said. The North's leader Kim Jong-Il made seven "field guidance" visits to the industrial city in 2010, it said.

The North, using plutonium extracted from its Yongbyon reactor, staged nuclear tests in 2006 and 2009. It is believed to have enough plutonium for six to eight atomic bombs.

The defector said Pyongyang was "likely to seek to enhance its nuclear capability via a third nuclear test" since the current arms programme "is behind on efficiency".

A spokesman for South Korea's intelligence agency said the information about a centrifuge plant at Heechon has not been confirmed.

The North shut down the Yongbyon complex in July 2007 under a six-nation aid-for-disarmament accord. But the six-party talks became bogged down in December 2008 over ways to verify denuclearisation.

In April 2009 Pyongyang abandoned the talks, a month before staging its second atomic weapons test. In September 2009 it announced it had reached the final stages of enriching uranium.

The United States accused the North in 2002 of operating a secret uranium enrichment plant, a charge which led to the breakdown of a previous nuclear disarmament accord.

China is trying to revive the six-party talks to ease tensions which flared after the North's deadly bombardment of a South Korean border island last November.

The issue is expected to be high on the agenda during President Hu Jintao's visit to Washington.

earlier related report
S. Korea investigates firms over trade with North
Seoul (AFP) Jan 19, 2011 - South Korea is investigating about 10 companies accused of importing North Korean goods in breach of a ban imposed last year over the sinking of a warship, an official said Wednesday.

The South suspended most cross-border trade last May when a Seoul-led multinational investigation found the North responsible for the sinking of the ship with the loss of 46 lives. It denies involvement.

Unification ministry spokeswoman Lee Jong-Joo said company officials are being questioned on suspicion of importing sea products, mushrooms and other items from the North via China.

The companies claimed they thought the products were from China.

Lee said the government plans to step up its crackdown on imports from North Korea starting next month. A jointly-run industrial estate at Kaesong in the North is excluded from the ban.

Cross-border relations soured after the warship sank near the disputed Yellow Sea border. They worsened even more after the North last November bombarded a border island, killing four South Koreans including civilians.

Direct inter-Korean trade shrank 54 percent from a year earlier to $117.8 million in 2010.

Consignment trade -- in which the North produced goods with raw materials from South Korea -- was down 22.5 percent at $317.5 million, the ministry said in a report.

Yonhap news agency said the cash-strapped North is pushing for a deal to send some 2,000 women workers to a Chinese wood processing plant to earn hard currency.

The deal was discussed on January 7 when a North Korean diplomat made a business trip to Mudanjiang in Heilongjiang province, which borders the North, it said.

Human rights groups have accused Pyongyang of forcing its people to work in inhumane conditions abroad to ease a foreign currency shortfall.