Tunisian Prime Minister Mohammed Ghannouchi has announced on state TV that he is resigning – a key demand of demonstrators.
He was speaking at a news conference in Tunis, after making a lengthy speech defending his record in government.
Mr Ghannouchi is seen as being too close to former President Zine al-Abidine Ben Ali, who was toppled in an uprising last month.
Mr Ghannouchi, 69, had served under Mr Ben Ali since 1999.