Tunis: Tunisia, birthplace of the Arab Spring revolutionary movement, was plunged into a new political crisis on Thursday when assassins shot an opposition party leader outside his home in a hail of gunfire.

It was the second political assassination in Tunisia since February, and quickly incited protests blaming Ennahda, the moderate Islamist party that leads the government. Crowds of protesters gathered outside the offices of the Interior Ministry in Tunis, the capital, calling on Ennahda to relinquish power, and security forces were deployed to contain them.

The Associated Press reported that protests erupted in other cities, including Sidi Bouzid, the impoverished town where the Tunisian revolution began, and in the nearby town of Meknassi, where angry demonstrators burned down the local Ennahda headquarters.

Ennahda issued a statement calling the assassination "cowardly and despicable". The leader of Ennahda, Rachid al-Ghannouchi, said on Tunisian radio: "This is a crime against the democratic transition of Tunisia. The classic question is: Who is behind this? I don't think that any political party would want this."