Updated

Tunisia's prime minister has labeled an ultraconservative Islamist group implicated in last year's U.S. Embassy attack a terrorist organization with links to al-Qaida.

Ali Larayedh said in a press conference Tuesday that the salafist group Ansar al-Sharia was considered a terrorist organization, based on seized documents, confessions and weapons captured from group members.

The group is believed to have helped to orchestrate an attack last September on the U.S. Embassy by protesters angered by a U.S. film mocking Islam; four assailants were killed in the clashes.

The group's leader, Seifallah Ben Hassine, was imprisoned by the former Tunisian regime until his release following the revolution that overthrew the secular dictatorship.

Ben Hassine is in hiding, and Larayedh urged other members of the group to quit or face the justice system.