New protests have broken out on the streets of Tunisia's capital, Tunis, hours before the expected announcement of a new national unity government.Police used water cannon to disperse several hundred demonstrators, calling for the party of ousted President Zine al-Abidine Ben Ali to relinquish power. The country has been in a state of emergency since he fled on Friday. Prime Minister Mohammed Ghannouchi has said an agreement between the political parties would be unveiled later.