Threats by US President Donald Trump to slap more punishing tariffs on Chinese goods are set to dominate a meeting of Asian business bigwigs and leaders that opens Wednesday in Hanoi.

The escalating trade spat between Washington and Beijing has caused global ripples -- and is being closely watched in Southeast Asia where many export-focused economies are set to gain from the fallout.

Trump has already imposed 25 percent customs duties on $50 billion worth of Chinese goods -- triggering a tit-for-tat response from Beijing -- and vowed last week to increase tariffs to hit $200 billion in Chinese imports "very soon".

The mounting dispute looms over a regional World Economic Forum (WEF) kicking off in the Vietnamese capital Wednesday morning where leaders from the Association of Southeast Asian Nations (ASEAN) and business executives are meeting.

"ASEAN countries don't want to count their chickens before they hatch, but I think they see it on a net basis as a gain for them because it means shifting manufacturing into Southeast Asia that was...(earlier) in China," Fred Burke, managing partner at Baker McKenzie in Vietnam, told AFP.

Rising labour costs in the world's second largest economy have already precipitated a push into countries like Vietnam and Cambodia where Adidas shoes, H&M T-shirts and Samsung phones are made on the cheap.

But the trade war has accelerated that process, with several Chinese firms turning to the region to produce items from bike parts to mattresses in a bid to avoid the new US tariffs.