They said the move would be an affront to democracy and could be a timebomb that would trigger a future civil war.
Speaking at a seminar at Kasetsart University yesterday, Thammasat University vice rector Nakharin Mektrairat said Mr Suthep's "people's council" idea was utopian and unworkable.
He also said the only option to defuse the escalating political conflict is for Prime Minister Yingluck Shinawatra to dissolve the House.
After the dissolution, Ms Yingluck's government should become a caretaker government with a commitment to push for national reform, he said.
"The idea to form a people's council is utopian," he said, questioning how council members would be recruited.
Kowit Wongsurawat, an academic at the Royal Institute's Moral and Political Science Academy, stressed the need to stick to democratic procedures under the constitution.
He said Mr Suthep's proposal strays from the charter, and invoking sections 3 and 7, which Mr Suthep has cited to back his proposal, could be open to wide interpretation and end up creating many problems.
Mr Kowit agreed the House should be dissolved and the government should find someone else who is acceptable to all sides to act as interim prime minister.
Chulalongkorn University political scientist Prapas Pintoptaeng said lessons should be learned from Latin America.
He said several countries there had tried to implement "people's councils" which failed because the councils become a mechanism for certain social groups to seize power.
He agreed with middle-class people who came out to curb the abuse of majority power in politics but disagreed with the move to escalate their demand for democracy to be changed into an "aristocratic regime" since he said it would only lead to violence in the end.
On Tuesday, Mr Suthep for the first time spelt out what he meant by his proposal for a "people's council" to run the country.
He said he wants to invoke Section 7 of the constitution, which would lead to the installation of a royally appointed prime minister and cabinet.
Mr Suthep said people from all walks of life will then choose representatives from various professions to form the council, which would work out policies and draw up legislation including charter amendments.
Democrat Party leader Abhisit Vejjajiva had proposed the invocation of Section 7 to end the political stalemate following the mass rally of the People's Alliance for Democracy to oust the Thaksin Shinawatra administration in 2006.
The idea was shot down however after His Majesty the King spoke about the issue on April 25 of that year.
His Majesty said Section 7 does not give the monarch authority to do anything he wants.
The section only refers to the democratic government with the King as Head of State, His Majesty said.
"If I do, they will say the King has acted beyond the scope of his duty. I never overstep my duty. If I overstep my duty, this is undemocratic," His Majesty said at the time.
Former charter drafter Seree Suwannapanon said yesterday it would be possible to invoke Section 7 to set up a people's council.
He said for this to happen, the prime minister must dissolve the House and then announce her resignation under Section 182 of the charter. This would confirm that cabinet ministers would vacate office en masse again under Section 180.
He said Prime Minister Yingluck should also announce that she will not remain in office as a caretaker prime minister, which would lead to a power vacuum as there would be no government.
This would pave the way for Section 7 of the charter to install an interim cabinet and set up a people's council.
But Worachet Pakeerut, a core leader of the Nitirat group and law lecturer at Thammasat University, disagreed with the proposal.
He said Section 181 of the charter stipulates that outgoing cabinet ministers shall remain in office until newly appointed ministers take office.
This means invocation of Section 7 was impracticable, he said.
Mr Worachet also said Section 7 has nothing to do with the installation of a prime minister by the King and was being misinterpreted.
Assessing the current political crisis, he said the government would eventually bow to the pressure and resign, but the country's problems will remain unsolved.The groups "who protect democracy" and have been defeated several times will regroup and come back in the next few years. A "civil war" could then break out, Mr Worachet predicted.
He said Mr Suthep's demands are uncompromising and not acceptable to the government. The best way out of the conflict is for Mr Suthep to compromise and take a step back.
Gothom Arya, from Mahidol University's Institute of Human Rights and Peace Studies, said the government's reaction to pressure from protesters must be within the parameters of the current constitution.
"Whatever is negotiated must be within this framework prescribed in sections 68 and 69 of the constitution," Mr Gothom said.
Section 68 of the charter stipulates that "no person shall exercise the rights and liberties prescribed in the constitution to overthrow the democratic regime of government with the King as Head of State."
Section 69 says that "a person shall have the right to resist peacefully any act committed for the acquisition of power to rule the country by a means which is not in accordance with the modes provided in this constitution".
Professor of politics and international studies at Australia's Murdoch University, Kevin Hewison, said Mr Suthep's demands could only succeed with another dose of military, judicial or palace support.
But if it succeeded and Mr Suthep seized power, he said the political reality will be considerably more authoritarian than his populist rhetoric suggests. "It will be a chilling despotism rather than new politics," said Mr Hewison.
Meanwhile, Deputy Prime Minister and Foreign Minister Surapong Tovichakchaikul called on Mr Suthep to surrender if he wants to discuss his plans with the government.
He stressed, however, that Mr Suthep's plan for a royally bestowed prime minster is unconstitutional.
"Mr Suthep's proposal is a figment of his imagination.
"He is sick and should see a doctor. He may have been under too much pressure from legal cases and the arrest warrant against him, causing his thinking to become abnormal," Mr Surapong said.