South Korea has questioned the North's explanation
North Korea has said it will expel South Korean workers from a mountain resort, in another sign of worsening relations between the two countries.
The move comes a month after a tourist from the South was shot dead by a soldier at Mount Kumgang, a special tourist zone in the North.
The South, which has suspended tours to the resort, described the North's decision as "incomprehensible".
Seoul has called for a joint inquiry into the shooting.
More than 260 southerners are working on Mount Kumgang - which had been regarded as one of the symbols of reconciliation between the two Koreas.
A military statement carried by North Korean media said the government would expel all South Koreans deemed "unnecessary" from the resort.
Although the reasons for the decision were not entirely clear, the statement accused Seoul of "misleading the public opinion at home and abroad".
It was also highly critical of South Korea's recently-elected President Lee Myung-bak.
"The reality shows that traitor Lee Myung-Bak is driving the frozen inter-Korean relations to a catastrophic phase," it said.
The South's Unification Ministry responded saying it regretted the North's decision, and renewed its criticism of Pyongyang for refusing to allow a joint inquiry into the shooting.
"We think it is regrettable that North Korea has taken incomprehensible actions instead of responding to a fact-finding investigation," the ministry said in a statement.
South Korean housewife Park Wang-ja, 53, was killed on 11 July on a beach near the resort.
North Korea said Mrs Park had strayed deep inside a restricted military zone, failed to heed warnings, and was shot while running away.
South Korea says forensic tests suggest she was shot while standing still or walking slowly, and photos of the beach area where she died show that it was not clearly defined as being out of bounds.
North Korea has refused to allow investigators from the South to visit the site.
Mrs Park's death overshadowed an announcement by Mr Lee that he wanted to reopen the stalled dialogue with North Korea.
Mr Lee's decision to proceed with diplomatic overtures to North Korea despite the shooting has drawn criticism in the South Korean media.
The Mount Kumgang resort has attracted more than one million South Korean visitors since 1998.
Access to the special tourism zone is tightly controlled, and its border heavily policed.