Tunisia's interim government has legalized the Islamist movement Ennahda, which had been banned under former President Zine El Abidine Ben Ali.
The action Tuesday will allow the movement to form a political party and take part in elections.
Ennahda's leader Rashid Ghannouchi returned to Tunisia on January 30 after nearly 20 years in exile.
He founded the movement in 1981 with others inspired by the Muslim Brotherhood that originated in Egypt.
Ennahda was tolerated in the initial years of Ben Ali's rule but faced a crackdown after 1989 elections in which the movement placed second to Ben Ali's ruling party
Tunisia's interim government has promised to hold new elections by mid-July.