North Korea's KCNA news agency this month quoted an official as warning that conservative elements in Seoul were upsetting relations by "letting loose malignant vituperation, slandering and defiling even the regime and system in the DPRK (North Korea)."
Another Unification Ministry official said the North had told 11 South Korean officials on Monday they would have to leave the site, finally forcing them out before dawn on Thursday.
"The North cited Unification Minister Kim Ha-joong's comments that without the resolution of the nuclear problem, there won't be any expansion of the Kaesong project," the official said.
Some 23,000 North Koreans work at the park about 70 km (45 miles) northwest of Seoul that houses nearly 70 South Korean factories producing clothing, shoes, watches and other goods for salaries a fraction of those in the South.
On Wednesday in Washington, South Korean Foreign Minister Yu Myung-hwan said that major powers were losing patience with Pyongyang's failure to produce a full accounting of its nuclear weapons programme as required in a 2005 deal.
The North, which battles chronic food shortages, had asked previous governments to supply it with massive amounts of rice and fertiliser but has yet to ask Lee's government.
Analysts said the North is still working out how to respond to Lee's demand that aid be linked to progress on humanitarian and nuclear issues.
Last month, the reclusive North allowed an unprecedented concert by the New York Philharmonic in Pyongyang, which some analysts said could lead to more openings in the isolated state.
North and South Korea on Thursday started without incident separate talks about energy and economic aid promised to the North as part of its pledge to eventually end operations at its ageing nuclear plant that produces weapons-grade plutonium.
