Tunisian President Kais Saied on Sunday officially replaced a key judicial watchdog and gave himself powers to sack judges, as well as banning them from going on strike.

Hours after the decree was published on Sunday, hundreds of protesters demonstrated in central Tunis to voice their fears for an independent judiciary.

Saied's decree came a week after he said he would dissolve the High Judicial Council (CSM), prompting a nationwide shutdown of courts by judges saying that would infringe on judicial independence.

The decree, establishing a new "Temporary Supreme Judicial Council" partly appointed by the president, also gives him powers to dismiss "any judge failing to do his professional duties."

Moreover, "it is forbidden for judges of all ranks to go on strike or hold any organized collective action that could disturb or delay the normal working of the courts," it read.

Saied last July sacked the government, suspended parliament and seized a range of powers before moving to rule by decree, sparking fears for what had been seen as the only democracy to emerge from the Arab Spring uprisings.