North Korea has warned it is preparing to conduct a third nuclear test and launch long-range rockets as payback for "hostility" from the US, declaring that Pyongyang is prepared to wage "full-fledged confrontation".

China, the country's only ally, has been forced to call for calm and restraint from the regime after the National Defence Committee in Pyongyang said it was conducting a "peaceful satellite mission", which the US claims is a test of long-range missiles.

The move comes two days after the UN Security Council agreed to expand sanctions against North Korea, as a response to a previous rocket launch, in December.

State media agency Korean Central News ran a report which read: "In the wake of desperate efforts on the part of the U.S. and its followers to block the victorious advance of the DPRK, they cooked up a "resolution" of the UN Security Council on Tuesday in wanton violation of the inviolable sovereignty of the DPRK."

North Korea's Foreign Ministry said in a statement: "The hostile forces are seriously mistaken if they think they can bring down the DPRK with sanctions and pressure, and such an attempt will always bring them a disgraceful defeat.

"The DPRK will continuously launch satellites for peaceful purposes to conquer space and become a world-level space power.

"The UNSC should apologize for its crime of seriously encroaching upon the independence of a sovereign state, following the US policy hostile to the DPRK in disregard of the universally recognized international laws, and repeal all the unreasonable "resolutions" at once."

south korea

South Korean Army soldiers patrol along the barbed-wire fence at the demilitarized zone on the border

China's Foreign Ministry spokesman Hong Lei called for "calm and restraint" on Thursday, urging the "relevant party" not to take any steps that would raise tensions, according to a Reuters report.

The timing seems deliberate to coincide with US President Barack Obama's inauguration. In 2008, shortly after the new President was sworn in, North Korea conducted similar tests, UN sanctions were applied and a nuclear test followed.

The South Korean news agency Yonhap said that South Korea was stepping up its monitoring of tunnels at North Korea's nuclear weapons test site, and Seoul officials warned a nuclear device could be “ready to detonate on a few days notice, but the decision to go ahead with the test will be a political one.”

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  • This image taken from KRT video shows an anchorwoman announcing the country's successful rocket launch in a TV program in Pyongyang, North Korea Wednesday, Dec. 12, 2012. (AP Photo/KRT via AP video)

  • In this Sunday, April 8, 2012 file photo, a crowd of media gather around a North Korean official on a road in front of North Korea's Unha-3 rocket, slated for liftoff between April 12-16, stands at Sohae Satellite Station in Tongchang-ri, North Korea. ((AP Photo/David Guttenfelder, File)

  • A clerk watches TV screens, airing file footage and reporting about North Korea's rocket launch, at an electronic shop in Seoul, South Korea, Wednesday, Dec. 12, 2012. (AP Photo/Lee Jin-man)

  • A man watches a TV screen broadcasting news on North Korea's rocket launch, at a railway station in Seoul on December 12, 2012. (JUNG YEON-JE/AFP/Getty Images)

  • Map locates the planned trajectory of the rocket that North Korea successfully fired;

  • Travellers watch a TV screen broadcasting news on North Korea's rocket launch, at a railway station in Seoul on December 12, 2012. (JUNG YEON-JE/AFP/Getty Images)

  • Travellers watch a TV screen broadcasting news on North Korea's rocket launch, at a railway station in Seoul on December 12, 2012. (JUNG YEON-JE/AFP/Getty Images)

  • A Chinese paramilitary officer stands guard outside the North Korean Embassy in Beijing on December 12, 2012. N(MARK RALSTON/AFP/Getty Images)

  • A clerk passes by TV screens, airing file footage and reporting about North Korea's rocket launch, at an electronic shop in Seoul, South Korea, Wednesday, Dec. 12, 2012. ((AP Photo/Lee Jin-man)

  • A man watches TV screen showing a North Korean TV anchorwoman announcing the success of a rocket launch, at an electronic shop in Seoul, South Korea, Wednesday, Dec. 12, 2012. (AP Photo/Lee Jin-man)

  • North Korean youths dance before the Pyongyang Grand Theatre in Pyongyang, North Korea, to celebrate a rocket launch on Wednesday, Dec. 12, 2012. (AP Photo/Jon Chol Jin)

  • North Korean staff at the Three Revolution Exhibition Hall walk outside the facilities after hearing the news of a rocket launch on Wednesday, Dec. 12, 2012 in Pyongyang, North Korea. (AP Photo/Kim Kwang Hyon)

  • Chinese paramilitary officers stand guard outside the North Korean Embassy in Beijing on December 12, 2012. (MARK RALSTON/AFP/Getty Images)