Nasar was born and grew up in Aleppo in Syria, and attended four years of university studies there at the University of Aleppo's Department of Mechanical Engineering. In 1980, he joined the Combatant Vanguard organisation, a radical offshoot of the Syrian Muslim Brotherhood, which was at the forefront in the Islamist uprising in Syria against Hafez Assad's government. Nasar was forced to flee Syria at the end of 1980. He then joined the Syrian Muslim Brotherhood organisation in exile, receiving training at their bases and safe houses in Iraq and Jordan. He is reported to have participated in the uprising of Hama in 1982. He emigrated to France and later to Spain in the mid-1980s.