North Korea has told its key ally China that it is prepared to stage one or two more nuclear tests this year in an effort to force the United States into diplomatic talks, a source said.

There could also be another rocket launch, said the source, who has direct access to the top levels of government in both Beijing and Pyongyang.

North Korea conducted its third nuclear test on Tuesday, drawing a stern warning from the US that it was a provocation.

“It’s all ready. A fourth and fifth nuclear test and a rocket launch could be conducted soon, possibly this year,” the source said, adding that the fourth nuclear test would be much larger than the third at an equivalent of 10 kilotons of TNT.

The source said the tests would be undertaken unless Washington held talks with North Korea and abandoned its policy of what Pyongyang sees as attempts at regime change.

North Korea also reiterated its longstanding desire for the US to sign a final peace agreement with it and establish diplomatic relations, the source said. The North remains technically at war with both the US and South Korea after the Korean war ended in 1953 with a truce.

Initial estimates of this week’s test from South Korea’s military put its yield at the equivalent of 6-7 kilotons, although a final assessment of yield and what material was used in the explosion may be weeks away.

The test, North Korea’s third since 2006, prompted warnings from Washington and others that more sanctions would be imposed. The UN security council has only just tightened sanctions after Pyongyang launched a long-range rocket in December. The North is banned under UN sanctions from developing missile or nuclear technology.

North Korea worked to ready its nuclear test site, about 60 miles from its border with China, throughout last year, according to commercially available satellite imagery. The images show that it may have already prepared for at least one more test.

“Based on satellite imagery that showed there were the same activities in two tunnels, they have one tunnel left after the latest test,” said Kune Y Suh, a nuclear engineering professor at Seoul National University.

Analysis of satellite imagery released on Friday by the specialist North Korea website 38North showed activity at a rocket site that appeared to indicate it was being prepared for an upcoming launch.

The North has said the test this week was a reaction to what it called “US hostility” following its rocket launch in December. Critics say the rocket launch was aimed at developing technology for an intercontinental ballistic missile.

“[North] Korea is not afraid of [further] sanctions,” the source said. “It is confident agricultural and economic reforms will boost grain harvests this year, reducing its food reliance on China.”

China signed up for sanctions after the North’s nuclear tests in 2006 and 2009 and for a UN security council resolution passed in January to condemn the latest rocket launch. However, Beijing has stopped short of abandoning all support for Pyongyang.

Sanctions have not discouraged North Korea from pursuing its nuclear ambitions, analysts said. “It is like watching the same movie over and over again,” said Lee Woo-young, a professor at the University of North Korean Studies in Seoul. “The idea that stronger sanctions make North Korea stop developing nuclear programmes isn’t effective in my view.”

The source with ties to Beijing and Pyongyang said China would again support UN sanctions. He declined to comment on what level of sanctions Beijing would be willing to endorse.

“When China supported UN sanctions … [North] Korea angrily called China a puppet of the United States,” he said. “There will be new sanctions which will be harsh. China is likely to agree to it,” he said, without elaborating.

He said Beijing would not cut food and fuel supplies to North Korea, a measure that it reportedly took after a previous nuclear test. The source said North Korea’s actions were a distraction for China’s leadership, which was concerned the escalations could inflame public opinion in China and hasten military buildups in the region.

http://www.guardian.co.uk/world/2013/feb/15/north-korea-more-nuclear-tests