China said on Tuesday that it regretted North Korea's announcement that it would restart a nuclear reactor to feed its atomic weapons programme, appealing for calm as tensions mount on the Korean peninsula.
"We have noticed the remarks of the DPRK and express our regret," Beijing's foreign ministry spokesman Hong Lei said at a regular briefing, using the North's official name.
"We call on relevant parties to keep calm and exercise restraint. The situation in the Korean peninsula is complicated and sensitive.
"The Chinese side's persistent position is to realise the denuclearisation of the peninsula and protect the peace and stability of the peninsula and Northeast Asia."
China has been North Korea's sole major ally for decades and is its biggest trading partner, providing key energy supplies to the poverty-stricken nation.
Beijing has repeatedly voiced similar appeals since North Korea carried out a nuclear test in February, its third in seven years, which prompted the UN Security Council to endorse tighter economic sanctions on the country.
But tensions on the peninsula have soared in recent days, with Pyongyang on Friday ordering missile units to standby, hours after nuclear-capable US B-2 stealth bombers were deployed in US joint military drills with South Korea.
The order came as US defense secretary Chuck Hagel said Washington would not be cowed by Pyongyang's bellicose threats and stood ready to respond to "any eventuality".