Supporters of Tunisia's ruling Islamist party on Tuesday attacked a demonstration by the country's main labour union, in the latest unrest two years after the revolution, an AFP photographer reported.
Several dozen assailants attacked members of the General Union of Tunisian Workers (UGTT) who were gathered outside the union's headquarters in Tunis to mark the 60th anniversary of the assassination of its founder, Farhat Hached.
The police intervened to separate the two sides, but 10 demonstrators were wounded in the attack, according to the trade union.
The interior ministry confirmed clashes had taken place between trade unionists and members of the League for the Protection of the Revolution, a group close to Ennahda that has developed a reputation for brutal violence.
In October, an opposition party accused the League, which claims as its mission to protect the aims of the revolution that toppled former dictator Zine El Abidine Ben Ali in January 2011, of beating a party official to death.
The UGTT's secretary general, Houcine Abassi, blamed the "enemies of democracy" for Tuesday's violence, and denounced what he said was an unprecedented attack against his organisation.
"They want to assassinate the UGTT on the day that it commemorates the assassination of Hached, who sacrificed his life for his people and his country," Abassi told private radio station Shems FM.
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He said such an attack had never been witnessed before, "neither during the time of (Tunisia's first president Habib) Bourguiba, nor of Ben Ali."
The League hit back, accusing the UGTT of provoking the clashes by attacking its members with batons when they tried to participate peacefully in the demonstration.
"Whenever there is a protest by the left, they insult us, they insult the government and Ennahda, even though no one has touched them. The reality is that they (leftist groups) are professional criminals," the group said on its Facebook page.
For its part, Ennahda, which heads Tunisia's ruling coalition after winning legislative elections in November last year, strongly criticised Tuesday's violence against the demonstrators, and called for restraint.
The latest unrest comes as clashes, strikes and attacks, including by hardline Islamists, have multiplied across Tunisia, plunging the country into a political impasse nearly two years after Ben Ali's ouster.
The UGTT organised a general strike and anti-government protests last week in the impoverished town of Siliana, southwest of the capital, over poor living conditions, which degenerated into five days of violence.
The union accused Ennahda supporters of instigating the unrest, in which youths erected barricades and hurled rocks and petrol bombs at the police, who responded by firing teargas and birdshot to disperse them.
More than 300 people were wounded.