North Korea's foreign minister said Tuesday that any decision to stage a further nuclear test would depend on the United States, as he held Washington responsible for scuppering denuclearisation efforts on the Korean peninsula.

"Whether we conduct additional nuclear tests is entirely up to the United States," Ri Yong-Ho told reporters on the sidelines of an Association of Southeast Asian Nations (ASEAN) meeting in Laos.

His comments came just hours after US Secretary of John Kerry, who was attending the same forum in Vientiane, warned of "real consequences" if Pyongyang pushes ahead with nuclear and missile tests.

The newly appointed Ri, who was making his overseas debut as the North's top diplomat, blamed the United States for the failure of the long-dormant six-party talks on Pyongyang's nuclear programme.

"The denuclearisation of the Korean Peninsula went out of the window because of the United States," he said.

Ri was previously the North's top negotiator to the six-party talks which brought together the two Koreas, the United States, Japan, Russia and China, and were last held in 2008.

"The key factor damaging the situation is the United States' hostile policies... and the problem is getting worse," he said, citing significantly toughened UN and US economic sanctions imposed after the North's fourth nuclear test in January.

"And recently they committed the most grave hostility by insulting our Dear Leader," Ri said, referring to the US decision to personally blacklist Kim Jong-Un over human rights abuses.

Despite the latest sanctions, North Korea has continued to carry out ballistic missile tests in violation of UN sanctions, and has made it clear that it intends to continue nuclear testing.

The issue of the North's weapons programme has dominated this week's talks in Vientiane -- a rare opportunity for all the members of the six-party process to be in the same room.

Kerry, who has held a flurry of closed-door meetings with his regional counterparts over the last two days, said there was unanimity on the need to curb the North's nuclear ambitions.

"Together we are determined... to make absolutely certain that DPRK (North Korea) understands that there are real consequences for these actions," Kerry told reporters.

Ri insisted that the North was a "responsible nuclear state" which would only strike if threatened, and he called on the United States to withdraw its troops from South Korea immediately.

US, N. Korea trade barbs over nuclear weapon tests
Vientiane (AFP) July 26, 2016 - North Korea said any decision to conduct another nuclear test depends entirely on the behaviour of the United States as the two sides traded blame Tuesday over tensions on the Korean peninsula.

Ri Yong-Ho, Pyongyang's newly appointed foreign minister, accused the US of being behind the failure of the long-dormant six-party talks on the country's nuclear programme.

His comments came after top Washington envoy John Kerry warned the North of "real consequences" if it continues nuclear and missile tests in defiance of UN sanctions, as the international community attempts to rein in the rogue nation.

"Whether we conduct additional nuclear tests is entirely up to the United States," Ri told reporters late Tuesday on the sidelines of a regional security forum in Laos which both he and Kerry attended.

"The denuclearisation of the Korean Peninsula went out of the window because of the United States," Ri said.

The hermit state carried out its fourth nuclear test in January, followed by a series of ballistic missile launches that sent tensions soaring across East Asia and beyond.

In response the UN Security Council slapped North Korea with its toughest sanctions to date in a unanimous decision even endorsed by China, its economic lifeline and diplomatic shield.

"The key factor damaging the situation is the United States' hostile policies... and the problem is getting worse," Ri said, citing the ramped up economic sanctions.

Despite the latest attempt by the international community to push it towards bankruptcy, North Korea has continued to carry out ballistic missile tests, and made it clear that it intends to continue nuclear testing.

With the tensions dominating talks in the Laos capital Vientiane, Kerry issued a stern warning to the North.

"Together we are determined... to make absolutely certain that DPRK (North Korea) understands that there are real consequences for these actions," Kerry said.

Analysts say this year's tests have shown the North making progress towards its goal of developing a credible strike threat against the US mainland, adding urgency to Washington's warnings.

Ri, a former nuclear negotiator, was making his overseas debut as North Korea's top diplomat at the gathering hosted by the 10-member Association of Southeast Asian Nations (ASEAN).

The meeting was a rare opportunity for the six parties involved in talks aimed at ending Pyongyang's nuclear programme -- the US, Russia, China, Japan and the two Koreas -- to be in the same room.

- 'Serious threat' -

Kerry held a flurry of closed-door meetings with his regional counterparts over the last two days.

"(The) issue that came up in nearly every meeting I had so far this week is the provocative and deeply concerning behaviour of the DPRK," he told reporters.

"North Korea's actions present a very serious threat, not just to this region but to international peace and security."

Earlier in the day, Kerry had referred to Iran and encouraged North Korea to follow its example.

"(Iran) was not going to pursue a nuclear weapon and, in exchange, would like to have sanctions lifted that had been put in place because of the evidence of that programme," Washington's top diplomat said.

Washington and Seoul agreed earlier this month to deploy a sophisticated anti-missile system in South Korea, a move which also spooked China and Russia, who worry about having the advanced US-made system on their doorstep.

The North, meanwhile, said it would take "physical action" -- a threat followed up with another missile test which it described as a simulated strike on the South.

North Korea's Ri met his Chinese counterpart Wang Yi on Monday on the sidelines of the Laos meeting but few details have been released.

Beijing is Pyongyang's main ally but its patience has worn thin.

China is, however, wary of pushing the North too far, fearing a regime collapse that could create a refugee crisis on its border and swing the regional balance of power towards the US.

The North Korean minister also hit out at the US decision to personally blacklist Kim Jong-Un over human rights abuses.

"Recently they committed the most grave hostility by insulting our Dear Leader," he said.