Prayuth will travel to Myanmar "as soon as possible", deputy foreign minister Don Pramudwinai told AFP, saying the trip could take place by the end of this month or early October.
"The Prime Minister is scheduled to visit Myanmar as his first foreign country because Myanmar currently chairs Asean," Don said, referring to the 10-nation Association of Southeast Asian Nations of which Thailand is also a member.
Prayuth is next expected to visit other Asean member states beginning with Malaysia, he added.
AFP