North Korea has at least one secret nuclear military facility, a panel of experts has told the UN Security Council in a report calling for tougher implementation of sanctions, diplomats said Monday.

The subterfuge work was probably started in the 1990s without raising suspicions, according to diplomats who have seen the report which could be discussed by a special Security Council sanctions committee in coming days.

The report is based on evidence from US scientist Siegfried Hecker who was taken to a secret site by the North Korean authorities last November.

Hecker has told of seeing hundreds of centrifuges at the Yongbyon complex when he went there. The report quoted him as saying that North Korea must have had foreign help to build the facility, one diplomat, speaking on condition of anonymity, told AFP.

"The report says that the centrifuges at Yongbyon must have been operated at at least one other facility before being moved there," the diplomat added.

"The equipment must have been started at least in the 1990s and had to have been made with outside help," said another diplomat, also speaking on condition of anonymity because the report has not been made public.

The panel of experts were set up to monitor two rounds of sanctions ordered by the UN Security Council against North Korea because of its nuclear bomb program.

"They said that more North Korea entities and individuals should be brought into the sanctions regime," said the diplomat.

The new names who would face a travel ban and assets freeze could be added to the sanctions regime without the need for a new UN Security Council resolution that China would probably oppose.

The United States and other western nations on the 15-member Security Council have already called for tighter sanctions.

The panel met Hecker after his visit to North Korea. None of the experts have been allowed to Yongbyon or any other North Korean facility.

North Korea has already said it has a plutonium bomb. It says it carried out bomb tests in 2006 and 2009.

It admitted that low-enriched uranium was being made at Yongbyon with the centrifuges after Hecker's visit. The North Korean authorities insist the uranium is for a "peaceful" light water reactor.

The UN experts made 10 recommendations, including adding more North Korean nuclear officials and companies to the sanctions list. They said North Korea state entities are using aliases to get equipment and that a wider selection of materials should be put on a list of banned imports, the diplomats said.

Neighboring countries should also tighten export controls to the North, the report was quoted as saying.

North Korea kicked UN nuclear inspectors out of Yongbyon in 2002 before withdrawing from the Non-Proliferation Treaty, the pact banning the spread of nuclear weapons.

The report did not name any country suspected of helping North Korea but the West has accused Iran and North Korea of working together on missile technology.

earlier related report
S. Korea's Lee urges North to improve ties
Seoul (AFP) Feb 1, 2011 - South Korea's President Lee Myung-Bak urged North Korea Tuesday to seize a "good chance" to improve relations in upcoming military talks, and raised the possibility of a summit with leader Kim Jong-Il.

"We can hold a summit if necessary... this is a good chance for North Korea," he said in his first direct response to recent peace overtures from Pyongyang.

After weeks of high tensions following the North's deadly November artillery bombardment of a South Korean border island, the two sides agreed last month to the military dialogue.

They will hold preparatory talks between colonels on February 8 to set the date, place and agenda for a higher-level military meeting, possibly between defence ministers.

But Seoul said the high-level meeting would only go ahead if Pyongyang took responsibility for two attacks last year and promised no repetition.

Apart from the shelling of Yeonpyeong island, which killed four people including civilians, the South accuses the North of torpedoing a warship last March with the loss of 46 lives -- a charge the North denies.

Lee said he believed a "strong response" to provocations could prevent any repetition and the North may now believe it did not have to take such actions.

"I have great expectations that this may be time for North Korea to change," he said.

"If the North shows willingness for sincere dialogue instead of military provocations, we can hold inter-Korean dialogue, economic exchanges and talk about the six-party talks."

The six-nation negotiations on the North's nuclear disarmament -- grouping the two Koreas, China, the United States, Russia and Japan -- have been stalled for more than two years.

The United States, South Korea and Japan say the North must improve cross-border ties before they can resume.

The two Koreas held summits in 2000 and 2007. But relations turned frosty after Lee came to power and ended a decade of near-unconditional aid to the impoverished and hunger-stricken communist state.

Lee expressed regret that the two nations are spending an "enormous budget" on an arms race, saying the North could probably overcome its persistent food shortages if it cut its defence budget by 20-30 percent.

The South for its part was spending nearly 30 trillion won ($27 billion) a year on defence "and if we can cut it by 10 percent, or three trillion won, a lot could be spent on education".

Three Seoul newspapers reported Tuesday that the North is building a new hovercraft base that would allow it to launch a quick invasion of South Korean islands near the disputed Yellow Sea border.

The base is under construction just 50-60 kilometres (30-35 miles) from Baengnyeong, the closest island to the North Korean coast, they cited military or government sources as saying.

The defence ministry declined to confirm the reports.

A government source told Chosun Ilbo that South Korean and US intelligence late last year detected construction at Koampo in Hwanghae province.

It could apparently accommodate up to 70 hovercraft, which could each carry a platoon of commandos and travel up to 90 kilometres per hour across the sea and tidal mudflats, the daily said.

Once the base is completed, North Korean troops would be able to land on the South's strategically important frontier islands in 30 to 40 minutes, it said.

The North's newly disclosed uranium enrichment plant is also fuelling security fears and complicating efforts to restart six-party dialogue.

The plant at Yongbyon was shown off last November to US visitors including scientist Siegfried Hecker.

The North says it will be part of a peaceful power project but Hecker and other experts say it could be converted to produce weapons-grade uranium.

Diplomats at the United Nations said a report by a panel of experts to the Security Council had concluded that the North must have at least one secret nuclear facility, in addition to the newly disclosed plant at Yongybon.