Thousands of Tunisians took to the streets of Bardo, near the capital Tunis, late Saturday, calling for the government led by the moderate Islamist Ennahda party to step down.
They were marking the end of a 40-day period of mourning after the assassination of opposition leader Mohamed Brahmi, shot dead outside his home on July 25.
Protesters gathered at Bab Saadoun, on the outskirts of Tunis, before marching to Bardo square, the scene of regular protests after the killing of Brahmi.
Demonstrators carrying portraits of Brahmi chanted slogans paying tribute to him and denouncing the government.
The authorities have blamed Brahmi’s killing, and the murder in February of another opposition figure, Chokri Belaid, on Salafist militants.
But many opposition supporters blame the government for having failed to crack down on Islamist extremists in the wake of Belaid’s killing.
Some members of Brahmi’s family have accused Ennahda itself of being behind his assassination, a charge the party has repeatedly denied.
Members of Brahmi’s family and a number of friends of Belaid marched at the head of the rally.