The supreme military command of the Democratic People's Republic of Korea said on Tuesday that the Korean War Armistice Agreement was null as tension continued to escalate on the Korean Peninsula.

The resolute statement came before a closed-door meeting of the United Nations Security Council, which was scheduled to be held in New York on Tuesday to discuss new sanctions against the DPRK in response to its Feb 12 nuclear test.

In the statement, an apparent response to ongoing US-Republic of Korea military exercises, a spokesperson for the Korean People's Army also said that the DPRK military will carry out more and stronger countermeasures, Xinhua News Agency reported.

ROK and US troops launched their annual joint drills on Friday, and the two-month-long Key Resolve/Foal Eagle exercises were held amid heightened tensions following the DPRK's third nuclear test, according to the Seoul-based Yonhap News Agency.

The Feb 12 nuclear test followed similar tests in 2006 and 2009.

The spokesperson in Pyongyang added that the DPRK has also decided to halt the work of its delegates at Panmunjom, where the two sides usually meet for communication and negotiations.

Panmunjom was where the Korean War Armistice Agreement was signed in July 1953, ending fighting in the three-year Korean War.

Serious protest

Shi Yuanhua, director of Center for Korean Studies under the Institute of International Studies at Fudan University in Shanghai, said the DPRK's latest harsh remarks, stronger than before, are a serious protest against the US-ROK joint drill, because the drill has mobilized more powerful weapons.

The standoff still sees no sign of abating as tensions are escalating, and "Pyongyang is also seeking to prompt Washington back to the negotiating table", Shi said.

Beijing on Tuesday responded to the ongoing US-ROK military exercises and media speculation of the DPRK's plan to stage a military drill.

China hopes all parties will do more to ease tension on the peninsula, as well as to promote peace and stability in the region, said Foreign Ministry spokeswoman Hua Chunying.

Military threats and international sanctions are "two of Washington's favorite ways" to deal with the DPRK, said Shi Yongming, a researcher on Asia-Pacific studies at the China Institute of International Relations.

"But the increasingly frequent joint drills by Washington and Seoul will further heighten Pyongyang's sense of insecurity, and may prompt it to go further down the nuclear road," Shi said.

UN meeting

Meanwhile, Russia, which holds the presidency of the 15-nation UN Security Council this month, was scheduled to chair the consultations regarding further responses to the DPRK's nuclear test, the UN media office announced.

The Chinese Foreign Ministry confirmed on Tuesday that China has maintained close communication on the issue with relevant parties on occasions including the UN Security Council.

China supports an appropriate UN Security Council response that shows its opposition to the DPRK's nuclear test, said Hua, the Foreign Ministry spokeswoman.

"The Security Council's response should be prudent and moderate, and should avoid further escalation,'' Hua said. The response should also safeguard peace and stability on the peninsula and Northeast Asia, she said.

Shi, from the CIIR, said the chance of dialogue was disappearing.

"The Korean Peninsula has been dragged into a malicious cycle of sanctions and confrontation", but dialogue is the best way out, Shi said.

Moscow is ready to back UN Security Council sanctions on the DPRK if they focus solely on Pyongyang's nuclear and rocket programs, a senior Russian diplomat said on Tuesday.

"It will be acceptable to us if the restrictive measures do not go beyond the boundaries of missile and nuclear issues" linked to the DPRK, Interfax News Agency quoted Deputy Foreign Minister Gennady Gatilov as saying.

ROK Foreign Ministry spokesman Cho Tai-young told reporters in Seoul that "considerable progress" had been made on the wording of a resolution, but added that "no full agreement has been reached yet".

Russian UN ambassador Vitaly Churkin, also the UN Security Council president for March, said earlier on Monday that the US had not yet circulated a draft text, but one was expected soon.

Xinhua, Reuters and AFP contributed to this story.