North Korea has said there is no room for dialogue with the South, on the day a South Korean envoy is in Beijing.
The statement, reported by South Korea's Yonhap news agency, referred to tensions persisting on the peninsula since last year.
South Korea's chief envoy for North Korea, Wi Sung-lac, is in Beijing for talks with his counterpart Wu Dawei.
Diplomacy has been focused on finding ways to revive stalled talks on ending the North's nuclear programme.
The two Koreas, China, Russia, Japan and the United States had been in the so-called six-party talks to this end, which collapsed in 2009.
Efforts to restart them have been stymied by two incidents last year: the alleged torpedoing by the North of the South's Cheonan warship on 26 March with the loss of 46 sailors, and the North's shelling of a South Korean island in November which killed several civilians.
Separately, North Korea and China are reported to have held a ground-breaking ceremony for a joint economic zone on their border.
The ceremony was reported by the South Korean news agency two days after North Korea said it had decided to set up the zone on two islands (Hwanggumphyong and Wihwa) in the Yalu river estuary.
The North Korean leader Kim Jong-il made a trip to China last month, in which Chinese reports said he had been invited to study China's rapid economic rise.
North Korea is beset by persistent shortages of food, power and raw materials.
The United States and the European Union have been researching the extent of the North's food shortages but have yet to decide on whether to send any food aid or not.