Tunisians ousted dictator Zine El Abidine Ben Ali in January 2011, triggering protests against autocrats in other Arab countries in what became known as the Arab Spring. A year ago, elections brought the moderate Islamist party Ennahda to power. But the social unrest that touched off the initial protests has persisted, compounded by religions tensions.
Opposition lawmakers boycotted a special legislative session marking the anniversary, saying the government has fallen short of the revolution's goals, "jobs, freedom and dignity." They also accused the government of allowing Islamists to attack intellectuals and artists.
In central Tunis, the capital, there were rival demonstrations for and against the government. Islamists chanted anti-American slogans "Obama, Obama, we all are Osama" addressing the U.S. president and referring to the former al-Qaida chief Osama bin Laden.
Soldiers surrounded public buildings, commercial centers and embassies.
A month ago, thousands of protesters stormed the American Embassy compound, and opposition party offices in Tunisia also have been attacked.
The national assembly's mandate expired on Tuesday, and the ruling coalition must now agree on how Tunisia will be managed until new legislative and presidential elections, expected mid-2013.
"The best gift we can give our people is to establish the foundation of a civil government that guarantees constitutional rights and liberties for generations to come, not just for the next elections," said President Moncef Marzouki at Tuesday's sparsely attended session.
In a video released Tuesday to mark the anniversary of the election, Tunisia's leading Islamist Abu Yadh accused the government of conspiring with the West.
"This government claims to belong to Islam, but Islam denies it," he said.