"The scientific field for national defence of the DPRK succeeded in the third underground nuclear test at the site for underground nuclear test in the northern part of the DPRK on Tuesday," said the news agency.
Pyongyang has already conducted similar nuclear tests in 2006 and 2009.
The Foreign Ministry said in the statement that it is the firm stand of the Chinese side to bring about denuclearization of the Korean Peninsula, prevent nuclear proliferation and safeguard peace and stability in Northeast Asia.
"We strongly urge the DPRK to honor its commitment to denuclearization and refrain from any move that may further worsen the situation. To safeguard peace and stability on the Peninsula and in Northeast Asia serves the common interests of all parties," said the statement.
It added, "The Chinese government calls on all parties to respond in a cool-headed manner and persist in resolving the issue of denuclearization of the Peninsula through dialogue and consultation within the context of the Six-Party Talks."
The six-party talks, a negotiation mechanism that includes the DPRK, the Republic of Korea, the United States, China, Japan and Russia, were launched in 2003 but stalled in December 2008. The DPRK quit the talks in April 2009.
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