The announcement came a week before Pyongyang is slated to head into talks with its neighbour and other regional powers which are pressing it to give up nuclear weapons.

North Korea's army also said it will 'selectively expel' South Koreans from a joint industrial zone in Kaesong, but stopped short of closing the South Korean-run factories that are a key source of hard currency for the impoverished nation.

North Korea warned nearly two weeks ago that it would end traffic across the heavily-armed border with its wealthy neighbour from Dec1, but this is the first time it has given details of what it will do.

More than 80 South Korean factories in Kaesong Industrial Complex employ about 35,000 North Korean workers.

The city is north of the border dividing the two countries, which technically remain at war as the 1950-53 Korean conflict ended in a truce, not with a peace treaty.

A tour programme in Kaesong began last December and has drawn about 110,000 tourists.

The first regular train service for half a century across the frontier began last December. It was hailed as a landmark in reconciliation between the two nations.

South Korea yesterday expressed 'serious regret' and urged the North to reverse its decision.

The tension on the long-divided Korean peninsula has been escalating since conservative South Korean President Lee Myung Bak took office in February, promising to invest heavily in the impoverished North on condition it moves to end development of an atomic arsenal.

The latest sabre-rattling came as United States Secretary of State Condoleezza Rice announced on Sunday that the next round of international talks on North Korea's nuclear programme will be on Dec8 in China.

Long-time North Korea watchers say the moves fit with a familiar pattern and may signal an upturn in relations with the US.

Over the years, they say, North Korea has divided its negotiations with the outside world into what some analysts call 'salami slices', maximizing its gains at each stage. If the opponent baulks, Pyongyang uses brinkmanship.

North Korea is using its old tactic of 'tongmi bongnam' - opening the door to the Americans while shutting it to the South Koreans. The idea is to drive a wedge between allies.

Unlike Mr Lee or, for most of his time in office, President George W. Bush, US President-elect Barack Obama has emphasised a policy of open and aggressive diplomacy with so-called rogue states.

It appears that the tactic has worked, with Seoul announcing yesterday that it would soon send steel to patch up power plants in the North.

Under a six-nation pact reached in February last year, the North was promised one million tonnes of heavy fuel oil, or equivalent-value aid, to repair power stations in return for disabling its plutonium-producing nuclear plants.

But the South postponed a shipment of 3,000 tonnes of steel pipes, citing delays in implementing the disarmament pact.

'(Steel) shipments will be made in the near future,' foreign ministry spokesman Moon Tae Young told reporters, adding that host China would soon formally announce the date for six-party talks.

The next round will focus on arrangements for inspections to verify a declaration of nuclear activities the North made in June as part of the disarmament pact.

The verification dispute is just the latest hurdle in tortuous negotiations, which began in 2003 and have often come close to breakdown. The forum groups the two Koreas, the US, China, Russia and Japan.

Analysts say North Korea feels it can win concessions from Mr Bush, who leaves office in January, as he is seeking a diplomatic legacy.

ASSOCIATED PRESS, REUTERS, AGENCE FRANCE-PRESSE, INTERNATIONAL HERALD TRIBUNE