Asean leaders have instructed officials to try and conclude a regionwide free trade pact by the end of this year, the grouping's top official said.
Leaders of the 10 member states will take stock of progress on the Regional Comprehensive Economic Partnership (RCEP) when they meet today. They include Singapore's Prime Minister Lee Hsien Loong, who arrived here yesterday.
Also on the agenda as leaders mark Asean's 50th anniversary are security in the Korean peninsula, Asean's relations with key partners and the challenge of extremism.
Giving an update on the RCEP in an interview, Asean secretary-general Le Luong Minh said progress has been made, and two important chapters in the 15-chapter agreement had been finalised in the latest round of negotiations.
Mr Minh noted that Asean remains an attractive trading partner amid a growing wave of populism and protectionism globally. The grouping had a combined gross domestic product of US$2.5 trillion (S$3.5 trillion) last year.
The RCEP, when sealed, would be the largest trade bloc in the world.
Said Mr Minh: "The RCEP is more important now not only for Asean economies and countries, but also the other participating countries."
Asean had proposed the trade agreement in 2011 as it sought to deepen economic integration with six of its key partners: Australia, China, India, Japan, New Zealand and South Korea.
Negotiations began in 2013, and there have been 17 rounds of talks so far, but the original 2015 deadline was missed. Mr Minh said there had been difficulties as some non-Asean countries involved did not have bilateral free trade agreements between them.
Besides RCEP, Asean is studying the possibility of free trade agreements with the Eurasian Economic Union and Canada.
Separately, Singapore's Foreign Minister Vivian Balakrishnan told reporters he and his counterparts also discussed the possibility of a trade deal with South America's leading trade bloc, Mercosur, that currently comprises Argentina, Brazil, Paraguay and Uruguay.
Seven of the RCEP partners were also in the Trans-Pacific Partnership, which United States President Donald Trump has pulled out of. But Mr Trump will attend Asean meetings in the Philippines this November, a move Mr Minh said signals the US leadership's commitment to the region and to its partnership with Asean. US Secretary of State Rex Tillerson will also host Asean foreign ministers in Washington next week.
Dr Balakrishnan said he and his counterparts hoped to emphasise the importance of US engagement in the region. "Asean as a whole remains a vital, viable, dynamic and growing area," he said. "It's an area that is replete with many business opportunities and the United States should not deprive itself of the opportunities that Asean represents."
At their retreat today, Asean leaders will also discuss ways to strengthen the grouping's unity and centrality in the region.