Prime Minister Lee Hsien Loong will arrive in Bangkok today to meet fellow South-east Asian leaders for the 34th Asean Summit.
He will be in the Thai capital until tomorrow.
The weekend summit is the first of two meetings among Asean leaders that Thailand will host as chairman of the regional grouping this year.
The leaders will meet to discuss ways to strengthen Asean centrality and unity, and how to take Asean forward, the Prime Minister's Office said in a statement.
The 10 Asean leaders will also exchange views on the bloc's external relations and discuss regional and international issues.
The theme for Thailand's chairmanship is centred on sustainability and partnerships.
The expected outcomes from this week's summit include a declaration of the leaders' vision for sustainability, along with an operational plan to resolve the problems of maritime pollution, as well as the drafting of a framework of ideas regarding the Indo-Pacific concept, the Bangkok Post reported.
Accompanying PM Lee are Foreign Minister Vivian Balakrishnan, Minister for Trade and Industry Chan Chun Sing and officials from both their ministries.
Trade will be high on the agenda, with trade and economic minis-ters expected to discuss progress on the Regional Comprehensive Economic Partnership, which will be the world's largest trade grouping, with the hope that negotiations can conclude by the end of this year.
In PM Lee's absence, Deputy Prime Minister and Finance Minister Heng Swee Keat will be the Acting Prime Minister.