South Korean soldiers stand guard in fog as a North Korean soldier (C far) is seen at the truce village of Panmunjom in the demilitarized zone dividing North and South Korea on February 27, 2013.

Beijing - China called for “calm and restraint” on Friday after North Korea responded to new UN sanctions with fresh threats of nuclear war and promises to scrap peace agreements.

“China calls on relevant parties to exercise calm and restraint, and avoid actions that might further escalate tensions,” foreign ministry spokeswoman Hua Chunying told reporters in Beijing.

“The current situation on the peninsula is highly complex and sensitive” and China “expresses concern”, she said, re-iterating Beijing's longstanding position.

Beijing is Pyongyang's sole major ally and by far its biggest trading partner, including being its primary energy supplier, but voted Thursday for the UN resolution that stiffened sanctions against the North following its nuclear test in February.

“We believe the resolution is a balanced one,” Hua said at a regular briefing. “China is objective and fair on this matter and has played a constructive role throughout the discussion at the Security Council.”

China has always “seriously” implemented UN Security Council resolutions, she added, and re-iterated Beijing's call for a return to the six-party talks that bring together the US, both Koreas, Japan and Russia. The forum has been moribund since 2009.

Chinese trade and aid have enabled the government in Pyongyang to survive since the 1950-53 Korean War, which historians estimate killed as many as 400 000 Chinese troops.

In China's strategic thinking, North Korea is a “buffer zone” that prevents the 28 500 US troops stationed in South Korea encroaching on its own border.

But analysts say that Pyongyang's actions mean the relationship risks becoming an irritant for Beijing. - AFP