More than 4,000 members of Tunisia's main trade union marched through the center of the capital on Saturday to denounce the Islamist-led government. Police fired tear gas to disperse the protest after it exceeded its time limit.
It was one of the largest demonstrations since tens of thousands marched through the capital demanding the ouster of Tunisia's long-reigning dictator more than a year earlier.
Saturday's clash was unrelated to a town hall meeting that U.S. Secretary of State Hillary Clinton conducted on the other end of Tunis on Saturday with young Tunisians to discuss the progress of democracy in North Africa. Tunisia was the first Arab nation to topple a longtime autocrat, leading to the Arab Spring.
The demonstration pointed to growing tensions between Tunisia's Islamist-led government and the leftist opposition, which has a strong presence in the union.
The protest was prompted by incidents at the union's offices around the country, which it blamed on members of Ennahda, the moderate Islamist party that won elections in October.
Municipal workers, including trash collectors, have been striking for the last four days, prompting unknown groups to dump garbage on union offices Tuesday.
"They want to terrorize us and instill fear in our hearts to keep us from defending our cause and rights, but we will not let them," said Hocine Abbassi, the secretary general of the UGTT, as the union is known by its French initials.
Ennahda has responded that its members had nothing to do with the incidents.
"The mobilization and provocation undertaken by certain parties in the UGTT for flagrantly political motives are a cause of concern," the party responded in a statement. The union has close ties to a number of left-wing opposition parties.
Protesters chanted that the new government had just stepped into the old one's repressive shoes and called for a new revolution.
"Citizens, wake up, the government is messing with you!" they chanted along the tree-line Bourguiba Avenue in the heart of the capital.
The march was peaceful for more than two hours before police dispersed the protesters with tear gas after the end of their allotted time.
The Ennahda Party dominated October's elections and joined in a coalition with two leftist parties to form a new government. The country is still wracked by unemployment, exacerbated by the unrest following the uprising and economic growth was negative last year.
The government also faces fierce opposition from the left-wing opposition and the old secular elite which regards it with suspicion.
On the other side of the city, Clinton congratulated Tunisia for one of the smoothest transitions to democracy during the Arab Spring uprisings of the past year and said the Islamists and other parties must learn to govern together.
"That means not just talking about tolerance and pluralism _ it means living it. And it's up to you to hold all your political parties to the same values," she said.
Associated Press writer Paul Schemm contributed to this report.