Tunisia's governing Islamists rebuffed on Thursday a plan by their party chief and prime minister to replace the government after unrest erupted over the killing of an opposition leader, deepening the worst crisis since the country's 2011 revolution.

Turmoil in the North African state that spawned the Arab Spring uprisings flared anew, with protesters setting ablaze the local headquarters of the main Islamist Ennahda party and a police station in the provincial town of Kelibia.

Police fired teargas to scatter protesters near the interior ministry in Tunis and stone-throwing youths in the southern mining town of Gafsa, where at least seven were injured. Crowds ransacked electronics shops in Sfax.