British foreign minister Dominic Raab will travel to Thailand on Wednesday to attend a meeting of 10 South East Asian countries, searching for new trading opportunities and stronger diplomatic ties ahead of Britain's exit from the European Union.

Raab, appointed last week as part of new Prime Minister Boris Johnson's pro-Brexit cabinet, will use his first international trip in his post to attend a meeting of Association of Southeast Asian Nations (ASEAN) foreign ministers in Bangkok.

"For too long, our trade focus has been on Europe. We need to expand our horizons, and raise our game. That means grasping the enormous global opportunities for the UK," he said in a statement ahead of the trip.

"This region is already worth $43.80 billion per year in trade with the UK - and there are opportunities for us to boost that trade to benefit UK businesses and consumers."

Under Johnson, Britain is due to leave the EU on October 31 regardless of whether it has a transition deal to preserve trading arrangments with the bloc. Critics say that would badly disrupt the flow of goods with the EU - its largest trading partner.

Advocates of Brexit have long argued that one of the biggest benefits of leaving the EU will be an ability to strike new bilateral trade deals rather than relying on EU-level agreements.

The ASEAN countries are Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand and Vietnam.