Democratic People's Republic of Korea launches a long range rocket launched into the air in this file still image taken from KRT video footage, released by Yonhap on February 7, 2016. [Photo/Agencies]

BEIJING -- China called for caution in both word and deed from all sides, to avoid escalating tension on the Korean peninsula, a foreign ministry spokesperson said Tuesday in Beijing.

Kim Jong Un, leader of the Democratic People's Republic of Korea (DPRK), said that the country plans to test a nuclear warhead and several ballistic rockets capable of carrying nuclear warheads, according to media reports on Tuesday.

"China's position on that issue is clear. We urge all sides to fulfill requirements of the UN security council, be prudent with their words and actions, and not take any action that would worsen tensions on the Korean peninsula," foreign ministry spokesperson Hong Lei said at a press briefing.

He reaffirmed China's willingness to implement the UN Security Council's resolutions concerning sanctions against the DPRK, saying that the government would inform those affected in a timely manner.

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Kim Jong Un says nuclear warhead test to be conducted 'in short time'

Top leader of the Democratic People's Republic of Korea (DPRK) Kim Jong Un said his country will conduct a nuclear warhead explosion test and a test-fire of ballistic rockets able to carry nuclear warheads "in a short time," the official KCNA news agency reported Tuesday.

Kim made the remarks when he guided an environmental simulation for reentry into atmosphere of the warhead tip of a ballistic missile, the report said.

The simulation was conducted to "verify the thermodynamic structural stability of newly-developed heat-resisting materials under the high pressure and thermal flow caused by aerodynamic heating" when a ballistic rocket reenters the atmosphere, the KCNA said, adding that the test results met all technical parameters.