North Korea shut down a handful of South Korean government-owned ventures at a joint tourism site, including a duty-free shop and the fire station, a tour official said Tuesday. North Korean authorities sealed keyholes and slapped stickers on the doors of five businesses at scenic northern Diamond Mountain, a resort that once was a symbol of a budding North-South cooperation, a South Korean business official said. South Korea halted the cross-border tours in 2008, and the communist North had threatened to seize South Korean businesses and to restart the stalled project with a new partner. Tuesday's move added to tensions between the two Koreas, which technically remain in a state of war. The seized facilities also included a reunion center for families separated by the 1950-53 Korean War, a cultural center where North Korean troupes performed for tourists and a spa, said Park Sung-wook of Hyundai Asan, a South Korean tour company whose facilities were not among those seized. North Korea also ordered four ethnic Koreans from China who had been working at the family reunion center out of the North within 24 hours. However, two South Korean technicians who work at the center but manage other ventures owned by Hyundai Asan and other private South Korean firms were not asked to leave, Park said. The two Koreas started the tour program more than a decade ago as part of reconciliation, but South Korea halted it in 2008 following the shooting death of a South Korean tourist by a North Korean soldier. The North recently expressed a willingness to restart the tour programs, which provided a much-needed influx of hard currency to the impoverished communist state. South Korea, however, says North Korea must carry out a joint investigation into the shooting death and outline measures to guarantee the safety of tourists.