SEOUL, South Korea (CNN) -- Eleven South Korean diplomats left an industrial park their country runs with North Korea on Thursday after North Korea "demanded their withdrawal," a spokesman for South Korea's government said.
The diplomats' departure follows comments made last week by South Korean Unification Minister Kim Ha-joong.
The diplomats left Kaesong, a North Korean city near the border between the two nations. Their departure follows comments made last week by South Korean Unification Minister Kim Ha-joong. He said it would be hard to expand the industrial complex without North Korean progress on denuclearization.
North Korea cited the minister's remarks as a reason for demanding that the South Korean diplomats leave, South Korea's Yonhap news agency reported.
The diplomats left around 1 a.m. Thursday, said Kim Ho-nyeon, spokesman for the South Korean Unification Ministry. Five South Korean civilian employees continue to work at the Kaesong office, the ministry said.
"We express deep concern over the North's unilateral demand," Kim said. "All responsibility resulting from the measure lies with the North Korean side."
The Kaesong industrial park is a potent sign of reconciliation efforts between the two Koreas. It hosts about 70 South Korean manufacturers and employs nearly 24,000 North Koreans, according to Yonhap. The two countries agreed last year to expand the complex.
North Korea also agreed last year to dismantle its nuclear program in exchange for economic aid and better relations with the United States.
The U.S. State Department says North Korea has done the majority of work related to disabling a plutonium-making facility but that it could do more.
The State Department said recently that North Korea has slowed the disabling process -- and that it has failed to provide a complete declaration of its nuclear program to the United States and its partners in talks on the nuclear issue -- Russia, China, Japan and South Korea.
North Korea has largely blamed the United States for the deadlock, saying it failed to honor its promise to remove North Korea from its list of countries that sponsor terrorism.
The State Department said North Korea must make a complete declaration of its nuclear program before the United States will remove it from the terrorism list.
"This declaration must include all nuclear weapons, programs, materials and facilities, including clarification of any proliferation activities," U.S. Assistant Secretary of State Christopher Hill told the Senate Foreign Relations Committee last month. E-mail to a friend