China has blamed South Korea for damaging "mutual trust" with its planned deployment of an advanced US missile defence system in the face of Beijing's opposition, Yonhap news agency said Monday.

Seoul and Washington announced earlier this month their decision to deploy the Terminal High Altitude Area Defense (THAAD) system in the South following recent North Korean missile and nuclear tests.

The plan to deploy the powerful system, which fires projectiles to smash into enemy missiles, angered Beijing and Moscow, which both see it as a US bid to flex its military muscle in the region.

"The recent behaviour from South Korea has undermined the foundation for our mutual trust," Chinese Foreign Minister Wang Yi told reporters ahead of a meeting late Sunday with his South Korean counterpart on the sidelines of a regional forum in Vientiane, Laos.

"I will hear what kind of practical actions South Korea will take to protect the unwavering relations between us," Yonhap quoted Wang as saying.

China is South Korea's largest export market and also a key partner in Seoul's efforts to curb North Korea's nuclear weapons programme.

At the meeting, South Korean Foreign Minister Yun Byung-Se acknowledged challenges in bilateral relations, but stressed that the THAAD deployment was purely defensive and posed no threat to China's security interests, Yonhap said, citing an unnamed Korean government official.

China, North Korea envoys hold talks in Laos
Vientiane (AFP) July 25, 2016 - Top envoys from China and North Korea held talks on Monday on the sidelines of a regional summit in Laos as tensions run high on the Korean peninsula over Pyongyang's nuclear programme.

North Korea's newly minted Foreign Minister Ri Yong-Ho, a former nuclear negotiator for the hermit state, and his Chinese counterpart Wang Yi met in the capital Vientiane.

It is the first time Ri has attended a major diplomatic gathering since his appointment in May.

A phalanx of security guards from both Laos and North Korea guarded the room where the meeting was taking place.

Relations between Beijing and Pyongyang have frayed this year after North Korea's fourth nuclear test and a series of missile launches put the region on edge.

In response to the new tests -- the most recent of which was last Tuesday -- Washington and Seoul announced plans to deploy a US missile defence system in South Korea, sparking fury in Pyongyang and concern in Beijing.

In the face of continued North Korean provocation, the United States spearheaded the drafting of a new UN resolution adopted unanimously in March by Security Council members, including China -- North Korea's main diplomatic protector and economic benefactor.

Washington has since urged China to use its leverage over Pyongyang to implement tougher sanctions and push the reclusive state towards bankruptcy.

But Beijing is 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 United States.

In June, Chinese president Xi Jinping stressed the importance of "friendly relations" with the North at a meeting with a top North Korean official.

North Korea formally withdrew in 2009 from six-party talks with South Korea, the United States, Russia, China and Japan that were aimed at tackling the nuclear issue.

Beijing wants the talks revived but Washington, Seoul and Tokyo all insist Pyongyang must first take some tangible step towards denuclearisation.

Beijing previously acted as a buffer between Pyongyang and the other five members, using cash to lure North Korea back to the negotiating table.

Both Ri and Wang are attending a diplomatic gathering organised by the 10-member Association of Southeast Nations (ASEAN).