SEOUL - NORTH Korea announced on Wednesday it would close its border with South Korea from next month, accusing Seoul of taking confrontation 'beyond the danger level'.

The communist state announced that a measure 'to strictly restrict and cut off all the overland passages' would take effect from December 1, the official Korean Central News Agency (KCNA) reported.

A total closure of the heavily fortified border would effectively shut down the Seoul-funded Kaesong industrial complex just north of the frontier.

Wednesday's announcement follows months of icy relations, including threats by the North to expel South Koreans from Kaesong in protest at the spreading of cross-border propaganda leaflets by Seoul activists.

KCNA said the move was in response to Seoul's failure to honour agreements reached at inter-Korean summits in 2000 and 2007. It said the border restrictions were the 'first step' in response.

The head of the North's delegation to inter-Korean military talks sent a notice of the ban to the South's armed forces on Wednesday, the KCNA report said.

'The South Korean puppet authorities' unchanged stand and attitude towards the historic two (summit) declarations have been finally confirmed', KCNA quoted the notice as saying.

'Such stand and attitude are leading to the grave wanton violation of all the North-South agreements made according to the declarations'.

Seoul's confrontational moves were 'going beyond the danger level', it added.

South Korea's defence ministry said it was checking the announcement.

Cross-border relations soured after conservative South Korean President Lee Myung Bak took office in February. He promised to take a firmer line with the North after a decade-long 'sunshine' engagement policy.

Mr Lee said he would review summit agreements between the North and his predecessors, which envisage joint economic projects costing tens of billions of dollars.

The North is also angry with South Korean activists who launch balloons carrying hundreds of thousands of leaflets across the heavily fortified border.

These criticise the North's leader Kim Jong Il as a dictator and repeat claims that he is in poor health - an especially sensitive topic.

South Korean officials have said he suffered a stroke in August but is recovering.

More than 32,000 North Koreans earning around 60 US dollars (S$90) a month work for 83 South Korean-owned factories at Kaesong, along with about 1,500 South Koreans.

It opened in 2005 as a symbol of reconciliation and earns the impoverished North tens of millions of dollars a year.

A second major joint project, the Mount Kumgang resort on the east coast, has already been shut down. Seoul suspended tours after North Korean soldiers in July shot dead a woman tourist who strayed into a restricted zone.

Representatives of the Kaesong companies are scheduled to meet Unification Minister Kim Ha Joong on Thursday to ask him to halt the spreading of leaflets.

The company officials, whose meeting was arranged before Wednesday's announcement, will also request contingency measures if Kaesong is shut down.

'The government will make all-out efforts to avoid the extreme situation in which Kaesong is closed down', the minister told parliament on Tuesday.

Kaesong and Kumgang are operated by South Korean company Hyundai Asan, which also operates day trips to Kaesong city near the industrial park.

'We don't expect tours to Kaesong to be affected by this announcement', a spokesman told AFP on Wednesday, adding that about 5,000 people have booked to take the trip next month. -- AFP