
The official gazette announced that law professor Sadeq Belaid would head the newly created "National Consultative Commission for a New Republic".
According to a report by AFP, Saied since last year has vowed to scrap the country’s 2014 constitution and draft a replacement to be put to referendum in July.
Saied has also created three other committees to focus on socio-economic issues, the judiciary and on national dialogue.
But many organisations including UGTT refused to take part.
Saied announced in early May the establishment of a long-awaited “national dialogue”, at the same time attacking the political parties he accuses of having plundered the country.
Many supported him for this decision however many protested against it and called it a "power grab".
Earlier on Saturday as well a protest was organised by the Free Constitutional party over the referendum.
The protest led by Abir Moussi, leader of the Free Constitutional Party.
Thousands marched from Bab Souika Square in the capital towards Kasbah Square, waving Tunisian flags.

A strike on Thursday was organised by The Tunisian General Labor Union (UGTT) over government economic reform plans, which brought much of the county to a standstill.
Flights were cancelled, public transport ground to a halt and government offices were closed in the nationwide strike.
"This strike is the culmination of a collective failure by more than 10 Tunisian governments, the UGTT, the International Monetary Fund and Tunisia's international partners" to restructure the economy, said Tunisian economist Fadhel Kaboub.
"It will serve as a reminder to the IMF that working people in Tunisia can only sustain so much economic pain", he added.
On Sunday, protesters marched through central Tunis to Avenue Habib Bourguiba, watched by a heavy police presence.
The protest was organised by the Salvation Front and included hundreds of people.
It was followed by the Free Constitutional Party's protest as well as the strike on Thursday by a powerful labour union.
People held placards and flags and shouted slogans.
"Saied must leave. The people on the streets are constantly against you Saied", activist Chaima Issa said.

Judges in Tunisia on Saturday extended their national strike for a third week in protest against a decision by Saied to sack 57 judges on June 1.
The president accused them of corruption and protecting terrorists charges that the Tunisian Judges Association said were mostly politically motivated.
The judges call it as President Kais Saied’s “interference” in the judiciary.
The country's main political parties say they will boycott the plebiscite.
But opposition to Saied remains fragmented, as shown by the separate demonstrations at the weekend.
His opponents say that plan for constitution would cement his hold on power.
The president's supporters say he is standing up to elite forces whose bungling and corruption have condemned Tunisia to a decade of political paralysis and economic stagnation.
They believe that the plan would benefit the country and help people.
The head of the country's constitution committee said on Saturday he will hand over the new draft of what he described as a democratic constitution to the president on Monday, ahead of a July 25 referendum.