The 35-member panel, chaired by veteran Prasong Soonsiri, approved a rough framework of the new constitution and insisted on the will of the defunct 1997 charter - that only allowed members of the House of Representatives to become prime minister.

The issue has become controversial in recent weeks because democracy advocates and academics have feared the junta may want to cling to power by backing a charter that opens the door for a non-elected premier.

The panel also backed a proposal to change the electoral system of the Senate and the House.

The current debate is whether the number of MPs should be reduced to 300 from 500 in the previous constitution and if senators should be appointed and their number halved to 100.

The panel agreed the charter should ease the rules that block censure debates on the executive branch.

The issue was widely criticised during the six-year premiership of Thaksin Shinawatra as the opposition failed to launch a censure debate against him, because it lacked enough MPs (200 of the 500) for such a motion.

During the meeting, Prasong urged panel members to complete the drafting by early June. He also asked that the language used in the new charter be simple, so it is easier for the general public to understand.