The joint parliament meeting which passed three charter amendment bills in the first reading might be unconstitutional and have violated meeting regulations, opposition chief whip Jurin Laksanavisit said on Thursday.
Mr Jurin said the move to amend the charter had a hidden agenda, that is to serve the political and economic interests of certain groups of people not the people of the country as a whole.
Moreover, after the parliament passed the charter bills in the first reading, the meeting was short of a quorum while discussing the number of days for the three scrutiny committees, each comprising 45 members, to complete their work.
Government MPs proposed that the scrutiny be finished in 15 days, while the opposition said the scrutiny process should take 60 days to complete.
At that moment, a quorum check was called. Only 295 lawmakers were present, short of the required 323.
Instead of adjourning the meeting, Parliament President Somsak Kiatsuranont allowed it to proceed and decided that the period for the scrutiny of the three bills was 15 days, Mr Jurin said.
Mr Somsak also instructed the three scrutiny committees to hold their first meetings on Thursday at 11pm.
Mr Jurin said this might have made the charter amendment process unconstitutional, as did Mr Somsak's action.
The opposition would look into the relevant laws and take some action, Mr Jurin said. He stopped short of saying whether it could be a petition to the Constitution Court.
At meetings of the scrutiny committees today, Senator Krit Arthitkaew of Kamphaeng Phet was appointed chairman of the committee to scrutinise the bill to amend Section 190.
Samart Kaewmeechai, a Pheu Thai MP, was appointed chairman of the committee to scrutinise the bill to amend sections concerning senators' terms and whether they should be appointed or elected.
Senator Direk Thuengfang, of Nonthaburi, was appointed to chair the committee to scrutinise the bill to amend Sections 68 and 237.
At the meeting of the Direk committee, three members from the Democrat Party - Wirat Kalayasiri, Nipit Intarasombat and Warong Dejwikrom - walked out.
Mr Wirat said at a press conference that since the joint sitting of parliament last night was short of a quorum the charter amendment process might be incomplete.
He said a new joint sitting should be held to complete the process.
If not, the Democrat Party might have to seek a ruling from the Constitution Court, Mr Wirat said.