Pyongyang would have a dialogue with the Trump administration if the "conditions are there", Yonhap news agency quoted a senior North Korean diplomat who handles relations with the US as saying.

Choe Son Hui, North Korea's foreign ministry director general for US affairs, made the comment to reporters in Beijing on Saturday.

"We'll have dialogue if the conditions are there," Choe said when asked if North Korea was preparing to hold talks with the US.

The comments by Choe, who is a veteran member of Pyongyang's team of nuclear negotiators, came amid stepped-up international efforts to press North Korea and ease tension over its pursuit of nuclear arms.

Choe was returning to North Korea from Norway where she attended the Track Two talks with former US government officials, according to Japanese media.

Reuters news agency reported that at least one former US government official took part in the meeting but the Trump administration was not involved.

A US State Department spokesperson said the United States remained open to talks with North Korea if it were to "cease all its illegal activities and aggressive behaviour in the region".

"We have been clear over the past 20 years that we seek nothing but a stable and economically prosperous Korean peninsula," the spokesman said in a statement sent to Reuters.

In April, US President Donald Trump warned that a "major, major conflict" with North Korea was possible, but that he would prefer a diplomatic outcome to the dispute over its nuclear and missile programmes.

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Trump later said he would be "honoured" to meet the North's leader, Kim Jong-un, under the right conditions.

South Korea's newly elected President Moon Jae-in has also expressed willingness to visit Pyongyang under the right circumstances.

North Korea has conducted five nuclear tests in defiance of UN and US sanctions and is also developing long-range missiles to deliver atomic weapons.