South Korea has proposed "final" talks with the North over the fate of the shuttered Kaesong joint industrial zone, suggesting it may permanently close the estate if the negotiations fail. The latest offer came after six recent rounds of talks aimed at reviving the Seoul-invested complex in North Korea produced few signs of progress. "We are offering the final talks to discuss the issue (of Kaesong)," said Ryoo Kihl-Jae, Seoul's unification minister in charge of cross-border affairs. Seoul would send a formal proposal across the border today, he said, without elaborating on when the talks would be held. The Kaesong complex, built in 2004 as a rare symbol of cooperation, survived previous crises. But it eventually became the most high-profile casualty of two months of elevated tensions after a nuclear test by the North in February which sparked international condemnation. Production at the estate, 10 kilometres over the border, has been suspended since North Korea withdrew its 53,000 workers from the zone in April. Ryoo reiterated that the South wants the North to accept responsibility for what Seoul insists was the unilateral closure of Kaesong by Pyongyang and give a written guarantee that it will never happen again. "Otherwise, we will be left with no choice but to make a grave decision to prevent even bigger damages on our companies in the future," he said. The North has said it was not responsible for the shutdown, arguing that its hand was forced by hostile South Korean actions and intimidation - in particular, a series of joint military exercises with the United States. Meanwhile, in an apparent gesture to lure Pyongyang to a fresh round of negotiations, Ryoo said Seoul would approve five shipments of humanitarian aid for the North worth 1.4 billion won (HK$9.7 million). The latest sixth round of talks held on Thursday ended in a bitter mood, with no date set for another meeting and the North's officials accusing their Seoul counterparts of being "arrogant".