TUNIS (Reuters) - Protesters set fire to the headquarters of Tunisia's Islamist ruling party Ennahda in the city of Sidi Bouzid after the assassination of opposition figure Mohamed Brahmi on Thursday, witnesses said.

Brahmi, who belonged to the nationalist and secular Popular Party, was shot dead outside his house in the capital Tunis. Ennahda strongly condemned the killing.

(Reporting by Tarek Amara; Editing by Alison Williams)