The lower house meeting on national reform came to an abrupt end on Wednesday due to the lack of a quorum of MPs.
House Speaker Chuan Leekpai adjourned the sitting after a count showed only 231 MPs in the chamber 20 minutes after the quorum bell had called them to the room.
A meeting of the House of Representatives needs at least 244 of the current 487 MPs to be present in the chamber.
The prime agenda for the meeting was progress on the plans for reform, which requires a report and debate in parliament every three months.
Pheu Thai MP Khrumanit Sangphum (Surin) asked the speaker for a headcount as the debate began, saying he saw few MPs from the government coalition bloc in attendance.
Mr Chuan paused the meeting to allow time for lawmakers outside the chamber to take their seats, but the number still fell short of a quorum.
Chief opposition whip Sutin Klungsang, of Pheu Thai, said after the meeting the opposition bloc would not rubber stamp the plans. He said coalition MPs showed their ignorance of the importance of the reform plans by failing to attend the meeting.
Chief government whip Wirat Rattanaset, of Palang Pracharath, claimed all MPs were at the parliament - they just had to attend the more than 30 House committee meetings also underway.