SEOUL, South Korea (AP) -- South Korea ruled out ending a lucrative, symbolic joint industrial complex in North Korea despite recent border closings and warned Wednesday it would take firm action if the North shuts the crossing again.
North Korea's military severed the only communications hot line between the two Koreas and has repeatedly restricted workers and cargo from crossing the border to protest South Korean-U.S. military drills that began March 9 and are to continue through Friday.
North Korean officials opened the border Tuesday after four days of restrictions and were allowing workers to pass through Wednesday, South Korean officials said.
The closures have raised concerns about mounting tensions between the two Koreas and the future of the industrial complex in the North Korean border city of Kaesong. The joint venture has been considered a promising example of inter-Korean cooperation after decades of animosity, and a key source of hard currency for the communist regime.
Relations between the Koreas have deteriorated steadily since South Korean President Lee Myung-bak took office a year ago with a new, tough policy toward the North. One by one, joint projects developed during the previous era of warmer ties have been suspended.
The Kaesong complex is the most prominent. It has been allowed to operate with a skeleton South Korean staff that must seek permission from the North before crossing the border to visit the zone.
South Korean companies that run about 100 factories rely on trucking in raw materials to produce the watches, shoes, kitchenware and electronic parts.
"We are not considering shutting down" the Kaesong complex, Unification Minister Hyun In-taek told reporters Wednesday.
Hyun, the Cabinet's chief policymaker on North Korea, warned that Seoul would consider another shutdown "very grave" and would "take necessary steps" to ensure workers and cargo can cross the border.
North Korea is also locked in a standoff with the international community over its nuclear weapons program and says it will launch a satellite into space next month. Some fear the launch is a cover for testing long-range missile technology.
In Beijing, Chinese Premier Wen Jiabao told North Korea's visiting premier, Kim Yong Il, that China will keep playing a positive role in six-nation talks aimed at ending the North's nuclear weapons program, state broadcaster CCTV reported.
Beijing is expected to push North Korea to return to the negotiating table. Talks stalled last year over how to verify its nuclear activities.
Wen's comments came a day after China voiced concern over mounting tensions ahead of Pyongyang's planned rocket launch.
Regional powers have urged North Korea to refrain from carrying out any launch, saying it would violate a U.N. Security Council resolution and could draw further sanctions.
On Wednesday, the North reasserted its right to launch a satellite into space, saying Russia, Iran, India and many other countries have been pursuing peaceful space programs.
"The immense space, where no border, boundary and jurisdiction exist, belongs to the entire world," the North's official Korean Central News Agency said.
South Korea's Defense Ministry said in a report to parliament Wednesday the North could instigate a naval skirmish off the peninsula's west coast around the same time as the launch.
North Korea refuses to recognize the maritime border demarcated by the United Nations at the end of the 1950-53 Korean War and wants it moved south. The border has been the site of two bloody naval skirmishes, in 1999 and 2002.
"Without fail, we will react" if North Korea crosses the sea border, Defense Minister Lee Sang-hee told lawmakers.
Associated Press writer Foster Klug in Washington contributed to this report.