China said Monday it would "faithfully" implement U.N. sanctions against North Korea's nuclear and missile programs, responding to remarks by the North's leader Kim Jong-un that Pyongyang will not use its nuclear weapons unless its sovereignty is jeopardized.

The remarks by Kim, announced during a rare congress of North Korea's ruling Workers' Party and reported by the North Korean media on Sunday, reaffirmed the North's bid to become a nuclear weapons state.

"Our republic is a responsible nuclear state that, as we made clear before, will not use nuclear weapons first unless aggressive hostile forces use nuclear weapons to invade our sovereignty," Kim was quoted as saying by North Korea's state media.

"I want to say that peace and stability of the Korean Peninsula, the denuclearization of the Korean Peninsula and the settlement of the Korean nuclear issue through negotiations and consultations serve peace and stability of Northeast Asia as well as international nuclear non-proliferation regime," China's foreign ministry spokesman Lu Kang told reporters.

"We hope that all parties could make efforts based on the consensus," Lu said.

Regarding China's stance on the North Korean claim as a nuclear weapons state, Lu said, "We maintain that all resolutions of the U.N. Security Council related to the Korean nuclear issue should be faithfully upheld by all relevant parties."

North Korea has conducted four nuclear tests since 2006.

International sanctions were tightened in March following the North's fourth nuclear test in January. (Yonhap)