North Korea issued another warning Friday, this time to South Korea against participating in the U.N. sanctions levied on the North. Pyongyang, a day earlier had warned the U.S. that it will go ahead with high level nuclear and missile tests targeting the U.S. after the U.N. expanded the sanctions following N.Korea's rocket launch in December.

In a statement issued by the Korean Central News Agency (KCNA), in the name of the Committee for the Peaceful Reunification of the Fatherland, North Korea pledged "physical counter-measures" against South Korea if it takes part in the U.N. sanctions regime. It said: "'Sanctions' mean a war and a declaration of war against us."

Referring to the South Korean leadership, the committee which is the North’s body for carrying forward inter-Korean dialogue said: "If the puppet group of traitors takes a direct part in the U.N. 'sanctions', the DPRK (North Korea) will take strong physical counter-measures against it."

Pyongyang’s threat against Seoul was the latest in a series of aggressive threats issued by it since the United Nation’s Security Council Tuesday tightened the sanctions against the North. In an unanimously adopted resolution, the UNSC condemned the Pyongyang’s Dec.12 rocket launch and expanded the sanctions imposed on North Korea following its nuclear tests in 2006 and 2009.

The U.S., which imposed a separate set of sanctions on the North Korea too, announced fresh economic restrictions following the North’s rocket launch. The U.S. imposed economic sanctions on two North Korean bank officials and a Hong Kong trading company that it accused of supporting Pyongyang's proliferation of weapons of mass destruction, as reported by Reuters.

The North furious over the sanctions, vowed to proceed with the nuclear tests and more missile and rocket launches aiming at the U.S.

“We do not hide that a variety of satellites and long-range rockets which will be launched by the DPRK one after another and a nuclear test of higher level, which will be carried out by it in the upcoming all-out action, a new phase of the anti-U.S. struggle that has lasted century after century, will target against the U.S., the sworn enemy of the Korean people,” the North had said.

The U.S. officials, reacting to the North’s Rhetoric said the statements from Pyongyang are “needlessly provocative.”

"We are very concerned with North Korea's continuing provocative behavior," U.S. Defense Secretary Leon Panetta said at a Pentagon news conference.

"We are fully prepared ... to deal with any kind of provocation from the North Koreans. But I hope in the end that they determine that it is better to make a choice to become part of the international family," he said according to Reuters.

South Korea and other countries who have been closely watching the North Korean nuclear arsenal programs believe that it has the technology to launch nuclear headed weapons targeting the U.S. cities. According to the South Korean intelligence agency, Pyongyang is technically ready for a third nuclear test.

China Calls For Restraint

Meanwhile, China, the North Korea’s major ally called for restraint and continuation of the dialogues to diffuse tension in the peninsula.

"We hope all relevant parties can see the big picture, maintain calm and restraint, further maintain contact and dialogue, and improve relations, while not taking actions to further complicate and escalate the situation," said Hong Lei, spokesman for the Chinese foreign ministry.

However, reports from the Chinese state media hinted that the Chinese government’s patience towards the North is waning.

"It seems that North Korea does not appreciate China's efforts," said the Global Times in an editorial, a sister publication of the official People's Daily.

"Just let North Korea be 'angry' ... China hopes for a stable peninsula, but it's not the end of the world if there's trouble there. This should be the baseline of China's position," Reuters has reported.