Mr Pornpetch told reporters that he issued an order today to include the selection of new prime minister as an agenda for the NLA meeting this Thursday.
The process to select the new prime minister will be based on the Provisional Constitution and past practices, he said.
NLA members are likely to vote in an opened-door session, he said, and the prime minister will be selected by a simple majority vote.
Asked whether it is possible for a member of the National Council for Peace and Order to become prime minister, Mr Pornpetch said the Provisional Constitution does not prohibit a public servant from holding a political position.
He noted that a commander-in-chief post is also regarded as a public service position.
The NLA president declined to comment on the possibility that Thai Army Chief Gen Prayuth Chan-ocha might hold two important public positions--one as head of the National Council for Peace and Order and the other as interim prime minister, which is seen by many parties as inappropriate.