A group of South Korean businessmen who own factories in the Kaesong industrial complex inside North Korea said Wednesday they want to visit to verify the North's claim that it had restarted some operations there on its own.

South Korea pulled out of the joint venture last year in response to the North's nuclear and missile tests, ending more than a decade of cooperation at the factory park, on the North's side of the demilitarized zone (DMZ), that was the last remaining symbol of inter-Korean cooperation.

North Korea's state-run websites said Friday that North Korean workers were operating in the district, adding that it was "nobody's business what we do in an industrial complex where our nation's sovereignty is exercised."