Seoul, Jan 1 (IANS): The chief nuclear envoys of South Korea, the US and Japan decried North Korea's renewed push to strengthen "self-defensive" capabilities as a "challenge" to the international community on Sunday, Seoul's foreign ministry said.

Seoul's top nuclear negotiator, Kim Gunn, and his US and Japanese counterparts, Sung Kim and Takehiro Funakoshi respectively, held three-way phone talks after North Korean leader Kim Jong-un called for increasing its nuclear arsenal and developing a new intercontinental ballistic missile during a key ruling party meeting, Yonhap news agency reported.

Their talks also followed the North's firing of shots from what it claimed to have been a super-large multiple rocket launcher on Saturday and Sunday.

"The North's statement on spurring efforts to strengthen so-called self-defensive capabilities in response to moves to isolate it is illogical and this would pose a challenge to the international community and only worsen the situation," the ministry said in a press release.

The North's proclaimed push to strengthen defense raised concerns that it would continue to engage in military provocations.

The three countries warned that the North's provocations would further deepen its isolation and make it face a stronger combined defence posture between the South and the US, and cooperation among the allies and Japan, and a "unified, stern" response from the international community, according to the ministry.

The three envoys also stressed that the "only" way for the North to ease its people's economic pain is to stop its provocations, return to dialogue, restore engagement with the outside world and channel resources -- splurged on its nuclear and missile programs -- into stabilising people's livelihoods.

They also reaffirmed the door for dialogue remains open, the ministry said.