North Korea has "no thoughts" of resuming six-party talks on its nuclear programme, a top Pyongyang official said Thursday in Beijing, despite the repeated urgings of its closest ally China.

The North quit the now-stalled negotiations aimed at curbing its nuclear weapons programme in 2009, and soon afterwards carried out its second atomic test. The talks are hosted by China, and include South Korea, the United States, Russia, and Japan.

Beijing, the North's main diplomatic protector and economic benefactor, wants to revive negotiations, although Washington, Seoul and Tokyo all insist Pyongyang -- which carried out two missile launches earlier this week -- must first take some tangible steps towards denuclearisation.

Choe Son-Hui, deputy director-general of the North American affairs bureau in Pyongyang's foreign ministry, said in Beijing: "For now, we have no thoughts about taking part in talks to discuss the DPRK's denuclearisation."

She was in the Chinese capital for an annual security forum, which includes representatives from each of the six parties.

"Under these circumstances where the US hostile policy is still there, DPRK is not in a position to talk about denuclearisation of the Korean peninsula," she told reporters in English outside the country's embassy, using its official name.

Ties between China and the North have become strained in recent years as Pyongyang has pressed ahead with internationally-condemned nuclear tests, and with Kim Jong-Un yet to visit Beijing since inheriting power from his father, who died in 2011.

After a string of failures in recent months, North Korea successfully tested two powerful Musudan medium-range missiles on Wednesday, one of which flew 400 kilometres (250 miles) into the Sea of Japan (East Sea).

Existing United Nations measures prohibit North Korea from using ballistic missile technology.

After Pyongyang conducted a fourth nuclear test on January 6, followed by a long-range rocket launch on February 7, the UN Security Council adopted its most punishing sanctions yet against North Korea.

Any further measures would require the support of veto-wielding permanent council member China, which has shied away from additional action in favour of calls for resuming the six-party talks.

In response to Choe's remarks, Chinese foreign ministry spokesperson Hua Chunying told a regular briefing that "all the six parties of the six party talks have the right to express their will".

She re-iterated Beijing's longstanding call for all parties to "create favourable conditions for an early resumption of the six-party talks".

Choe denied that Pyongyang felt a lack of support from its neighbour.

"We are not at all disappointed by the Chinese," she said.

"China is doing what she has to do, and we are doing what we have to do."