BANGKOK: US Secretary of State Mike Pompeo insisted Thursday that Washington was not asking Southeast Asian nations to "choose" between his country and rival power China, as he trailed a rebooted security and trade strategy at a Bangkok summit.

The denuclearisation of the Korean Peninsula, a bitter trade war between the superpowers and open access to contested seas dominated talks between Pompeo and his Chinese counterpart Wang Yi on the sidelines of a summit of Southeast Asia's top diplomats.

Pompeo is in Bangkok tasked with reassuring Asian allies that the US remains a key player in the region, as China builds up its military presence in disputed seas and airspace and cements its economic and political primacy across the region.

The rivalry between the two superpowers is framed by a trade war that has cramped global growth and seeded uncertainty across Asia's economies.

Pompeo and Wang shook hands and smiled before the brief talks.

Both later played down the rifts between their nations, with Wang describing the meeting as a "deep communication" that "has helped to increase our mutual understanding".

"There may be various kinds of issues and problems between China and the United States," he said.

"But no matter how many problems.. we all need to sit down and continue to communicate."

In a tweet Pompeo said he had "an in-depth exchange of views" with Wang -- including on North Korea -- adding "when it advances U.S. interests, we are ready to cooperate with China."

Pompeo also insisted the US was not prodding Southeast Asian nations to "choose between countries".

"Our engagement in this region has not been and will not be a zero-sum exercise," he said in short remarks at the opening of a meeting with the 10-member ASEAN states.

China on Thursday said it had begun buying more US farm goods, a day after trade negotiations resumed in Shanghai in a bid to find a way through the tit-for-tat tariff war.

- Beijing's orbit -

Among the tension points with China is the South China Sea, an area Beijing believes to be its orbit and outside the US sphere of influence.

China is accused of deploying warships, militarising outposts and ramming fishing vessels in contested waters, one of the world's key shipping routes and which the US is desperate to keep open.

Several rival Southeast Asian claimants to the sea say Beijing has used its military, economic and diplomatic heft to slow progress on a binding Code of Conduct in the flashpoint zone.

The US wants guarantees of open seas and has offered its support to several of the claimant nations in the face of Chinese aggression.

Washington has been closely following reports that Cambodia has struck a deal allowing China to use a strategically key naval base with ready access to the South China Sea.

But in his meeting with ASEAN foreign ministers, Pompeo said Cambodia had strongly refuted the claim.

"The US weclomes Cambodia's strong defence of its national sovereignty," Pompeo told reporters on Thursday evening.

The administration of President Donald Trump, which early on pulled out from a massive Asia-Pacific trade pact, is pushing an "Indo-Pacific" strategy of bilateral commercial deals and security support for the region.

China rebuffs US intentions in the region and is the driving force behind a separate trade-pact which sweeps in Southeast Asia.

On Wednesday Wang described Southeast Asia as China's "neighbourhood" and in a barely concealed swipe at the US urged "non-regional countries" to not "sow distrust" in the area.

US-led efforts to tease North Korea into ending its nuclear ambitions were also covered in discussions, with Beijing's leading diplomat welcoming the high-visibility summits between Donald Trump and Kim Jong-Un.

But Pompeo expressed "regret" that his North Korean counterpart was not at the Bangkok summit for further talks but said he was optimistic fresh discussions were on the horizon.

On Friday, America's top diplomat will meet his South Korean and Japanese counterparts hoping to help defuse a bitter diplomatic row between two key US allies that has billowed out into a trade dispute.

The issue has its roots a decades-long quarrel over Japanese forced labour during World War II. —AFP