North Korea has rejected South Korea's demand for talks on a jointly run factory park that's been closed nearly a month.

Pyongyang on Friday batted back an earlier threat from Seoul with its own warning of "grave measures" over the last major symbol of inter-Korean cooperation.

Seoul on Thursday had used the same language to push Pyongyang to accept its demand for talks. Neither capital is providing specifics of what those measures might be. But the war of words calls into question the future of the complex.

The park in the North Korean border town of Kaesong is the most significant casualty so far in the recent deterioration of relations between the Koreas.

Pyongyang barred South Korean managers from entering North Korea and pulled out its workers early this month.