China on Friday called for calm and restraint on the Korean Peninsula, as analysts said the risk of a flashpoint is increasing.

The Democratic People's Republic of Korea announced that it will sever a military hotline with the Republic of Korea, nullify non-aggression agreements between the two and totally abrogate the joint declaration on the denuclearization of the peninsula.

The statement from the DPRK's Committee for the Peaceful Reunification of Korea came hours after the United Nations Security Council on Thursday passed a new resolution expanding sanctions on the DPRK for its Feb 12 nuclear test.

Chinese Foreign Ministry spokeswoman Hua Chunying told reporters at a daily briefing on Friday that parties should "exercise calm and restraint, and avoid actions that might further escalate tensions," describing the situation as "highly complex and sensitive".

"Safeguarding peace and security on the Korean Peninsula and Northeast Asia is in accordance with the common interests of the whole international society," Hua said.

Given the rising tensions on the peninsula, the possibility that a "small-scale military conflict may happen accidentally" cannot be ruled out, said Yu Shaohua, director of the Department for Asia-Pacific Security and Cooperation Studies at the China Institute of International Studies.

But a massive military confrontation is unlikely, she said.

Neither the DPRK nor the ROK wants to take the initiative to militarily provoke the other, and they are now mostly verbally targeting each other, she said.

The latest UN sanctions may help prevent the DPRK from conducting further nuclear tests, but sanctions alone cannot solve the problem. "Peaceful talks need to be created," she said.

Ted Carpenter, senior researcher at the Cato Institute, a US think tank, said, "Washington and its allies need to accept that it may be too dangerous to try to isolate a nuclear power instead of trying to establish a constructive relationship" with the DPRK.

The ROK expressed its deep regret on Friday over the DPRK's latest statement, Yonhap news agency reported.

"It is regrettable" that Pyongyang has "unilaterally annulled past non-aggression and denuclearization agreements and moved to escalate tensions", ROK Ministry of Unification spokesman Kim Hyung-suk was quoted by Yonhap as saying.

The official said the DPRK should take steps to acknowledge and respect formal agreements that can lead to the building of trust.

The UN Security Council unanimously adopted a resolution with tough new sanctions on Thursday, which is the 15-member council's fifth involving the DPRK since 2006.

It imposes additional financial curbs on the DPRK, such as blocking transactions that could aid its nuclear and ballistic missile activity, prohibiting bulk transfers of cash, restricting access to Pyongyang's financial sector and banning exports of luxury goods to the country.

Li Baodong, China's permanent representative to the UN, said that while it was "an important step" for the council to approve the new sanctions, "adoption of the resolution itself is not enough".

"This resolution is a very important step, but one step cannot make a journey," Li told reporters after Thursday's council vote. "We need a comprehensive strategy to bring the situation back to dialogue. We need wisdom, persistence and perseverance.

"We want to see full implementation of the resolution," the Chinese diplomat said, urging resumption of the long-stalled Six-Party Talks aimed at denuclearizing the Korean Peninsula.

On Friday in Pyongyang, state media reiterated a warning that it will launch pre-emptive nuclear strikes on the US.

White House spokesman Jay Carney said the US is "fully capable" of defending itself against a ballistic missile attack from the DPRK.

The top US envoy on the DPRK issue, Glyn Davies, cautioned Pyongyang not to miscalculate, saying the US will take necessary steps to defend itself and its allies, including the ROK, where more than 30,000 US troops are based.

Russia's UN Ambassador Vitaly Churkin warned that "new threats or trying to build up the military muscle in the region ... might be taking us away from the need to resume Six-Party Talks", which he added must be an international priority for all countries.

Xinhua and AP contributed to this story.