Tunisia's President Kais Saied on Saturday indicated he was preparing to change the country's constitution, but said he would only do so using existing constitutional means, seven weeks after he seized powers in moves his foes called a coup.

Speaking live on television in a central Tunis boulevard, Saied said he respected the 2014 democratic constitution but that it was not eternal and could be amended.

"Amendments must be made within the framework of the constitution," he told the Sky News Arabia channel and Tunisian state television.

One of Saied's advisers told Reuters on Wednesday the president was planning to suspend the constitution and offer an amended version via a referendum, prompting opposition from political parties and the country's powerful main labour union.

Anxiety has been growing, both internally and among Western democracies that have supported Tunisia's public finances, over Saied's intentions since his July 25 announcement that he was sacking the prime minister and suspending parliament.

The former constitutional law professor justified those moves by citing emergency measures in the constitution that his critics and many legal scholars said did not support his intervention.

Though he indefinitely extended the measures after a month, he has yet to appoint a new government or make any clear declaration of his long-term intentions, as Tunisia struggles to confront a rolling economic crisis.

His intervention drew widespread support after years of political paralysis, but it has thrust Tunisia into crisis a decade after it threw off autocracy and embraced democracy in the revolution that triggered the Arab Spring.

(Reporting by Tarek Amara and Nayera Abdallah; Writing by Angus McDowall; Editing by Paul Simao)