Tunisian opposition politician Mohamed Brahmi has been shot dead outside his home in the capital, Tunis, reports say.
Mr Brahmi led the nationalist Movement of the People party. It is Tunisia's second assassination of an opposition party leader this year.
In February, prominent secular politician Chokri Belaid was also shot outside his house in Tunis. His murder sparked angry protests and prompted the resignation of PM Hamadi Jebali. Mr Brahmi was a member of the National Constituent Assembly, which is drafting a new constitution.
It is not known yet who is behind the attack.