North Korea denounced South Korea on Monday for stating its commitment to denuclearization of the Korean Peninsula in a joint declaration with Japan and China following their trilateral summit, casting it as a "mockery" of the region and the international community.

The North's foreign ministry issued the statement hours after President Yoon Suk Yeol, Japanese Prime Minister Fumio Kishida and Chinese Premier Li Qiang held the trilateral summit in Seoul and reaffirmed their commitment to promote peace and stability on the Korean Peninsula.

In the joint declaration, the three sides reiterated positions on denuclearization of the Korean Peninsula and the abduction issue, respectively, and continue efforts for the political settlement of the peninsula issue.

"It is a mockery of and trickery against the regional countries and the international community that the ROK is talking about 'denuclearization,' 'peace and stability,'" a spokesperson at the North's foreign ministry said in the statement released by the Korean Central News Agency.

ROK stands for the Republic of Korea, South Korea's official name.

"The complete denuclearization of the Korean Peninsula has already died out theoretically, practically and physically," the ministry said.

The North then accused the South of being the root cause for creating "a grave security crisis" on and beyond the peninsula by "frantically strengthening military alliance for aggression."

"The DPRK Foreign Ministry strongly denounces and rejects it (denuclearization commitment) as a blatant challenge to the sovereignty of the DPRK and wanton interference in its internal affairs."

DPRK stands for the North's official name, the Democratic People's Republic of Korea.

North Korea will "firmly defend" its sovereignty and national dignity from any attempts by "hostile forces" to deny its sovereignty, the statement read.

Hours before the three-way summit took place, the North announced its plan to launch a space rocket carrying a military spy satellite by notifying Tokyo of such a plan sometime before June 4. (Yonhap)