(Adds Ennahda statement, more clashes in paras 6-8)
By Tarek Amara
TUNIS, Dec 4 (Reuters) - Tunisian police broke up fighting in Tunis on Tuesday when pro-government Islamists attacked labour union members they blamed for inciting protests last week against the Islamist government.
Several hundred Islamists with knives and sticks charged a gathering of members of Tunisia's biggest union, UGTT, in the capital and broke windows at its offices with stones, a Reuters witness said. Police then intervened to separate the two groups.
About 10 people were hurt in the clashes, the witness said.
"UGTT, you are thieves, you want to destroy the country," the Islamists chanted. They also carried banners.
Hundreds of UGTT members, who backed days of protests over lack of jobs and development in the deprived town Siliana last week, had been chanting slogans in the streets by the UGTT headquarters calling for a general strike and the downfall of the government led by the Islamist Ennahda party.
"Ennahda will end up like Ben Ali. They have not chosen their enemy well," said one demonstrator, referring to Zine al-Abidine Ben Ali, the veteran autocrat toppled in the Arab Spring uprising in January 2011.
Later, Islamists and leftists threw bottles and stones at each other near the government's headquarters where some 2,000 unionists had gathered to demonstrate against Ennahda prime minister Hamadi Jebali.
The protests were the fiercest since conservative Salafi Islamists attacked the U.S. embassy in Tunis in September over an anti-Islam film made in California, in violence that left four people dead.
The clashes on Tuesday did not appear to involve Salafis.
"This is a message from Ennahda to stop union activism. It's the same method used by Ben Ali," said Fethi Debek, a member of the UGTT executive.
Ennahda came to power after the ousting of Ben Ali, whose police state had repressed Islamists and promoted secularism.
It distanced itself from the attack on the unionists, who were gathering to commemorate the death of a famed labour leader, calling for "self-restraint".
"Ennahda strongly condemns the violent attack on protesters and expresses its solidarity with all those injured," it said.
The headquarters of all national bodies needed to be "emptied of all tools of violence", the party said.
Ennahda accused leftists who lost last year's elections of fomenting the unrest in Siliana by provoking Tunisians in impoverished areas into confrontations that would drive away foreign investors.
The protests, in which at least 252 people being injured - including some cases of blinding by birdshot - began after a UGTT call to take to the streets to demand jobs, investment and the removal of Ennahda's Islamist governor of the province.
The government on Saturday temporarily removed the local governor, promised jobs to victims of the 2010 uprising, and police stopped using birdshot after criticism of "excessive force" from U.N. Rights Commissioner Navi Pillay.
The shift to slogans against the Islamists in Siliana seemed to wrong-foot the government, which has been absorbed so far with violent disputes between Salafis and liberal Muslims over the future of a country that was once a bastion of Arab secularism, and with securing funding to meet budget targets.
The Western-backed government secured international funds last week to shore up its economy which is suffering from the financial crisis in Europe, Tunisia's main trading partner. (Reporting by Tarek Amara; Writing by Andrew Hammond; Editing by Louise Ireland)