A summit of Southeast Asian leaders has opened, overshadowed by the Philippine leader's intemperate comments aimed at President Barack Obama.

Philippine President Rodrigo Duterte occupied center stage on the eve of the summit when he made comments Monday about Obama that included a "son of a bitch" remark.

He was again in the spotlight Tuesday when he trooped into a conference hall in the Laotian capital of Vientiane wearing a traditional Filipino shirt with sleeves rolled up. The other leaders were dressed in dark business suits.

Duterte rolled his sleeves down when the Laotian president gave his speech to open the Association of Southeast Asian Nations summit.

Obama, who arrived in Vientiane on Monday night, will attend a summit Thursday between leaders from ASEAN and countries including China and Russia.