BEIJING, April 22 -- China on Tuesday called on parties concerned to remain calm and restrained and adhere to the goal of realizing a nuclear-free Korean Peninsula.

Foreign Ministry spokesman Qin Gang made the remarks at a regular press briefing.

The Defense Ministry of the Republic of Korea (ROK) on Tuesday warned of a "surprise" nuclear test by the Democratic People's Republic of Korea (DPRK), citing increased activity in its main underground test site.

ROK Defense Ministry spokesman Kim Min-seok told a routine press briefing that a lot of activity has been detected in and around the Punggye-ri test site in the northeastern DPRK, where its third test was conducted in February last year.

Qin said China has taken note of relevant reports. He said that under current circumstances, parties concerned should exercise calm and restraint and continue to push forward denuclearization on the Korean Peninsula.

He also called on parties concerned to resolve problems through dialogue and negotiation, and remain firm in safeguarding peace and stability on the peninsula.

After the the DPRK fired two Rodong medium-range ballistic missiles on March 26, the UN Security Council held an extraordinary session, censuring the country's violation of UN resolutions that have banned Pyongyang from testing ballistic missile technology.

In response, the DPRK's Foreign Ministry issued a warning on March 30, saying that it would "not rule out a new form of nuclear test" to bolster its nuclear deterrence, accusing the United States of "acting rashly" at the UN Security Council.