A committee appointed by Thailand's military rulers to draft a new constitution says a 200-member Senate will be nominated and not elected in what critics call a setback for Thai democracy.

The constitutional drafting committee says new senators will be chosen from pools of candidates, including former premiers, ex-military leaders and representatives from different professions.

Under the last constitution, which was abolished after a coup in May last year, half of the Senate was directly elected and the rest appointed.

The drafting process is being carried out by a 36-person committee hand-picked by the junta.

Critics say Thursday the action was designed to limit the power of elected politicians in the parliament.

Once finished, the constitutional draft will be reviewed by the junta.