* Protest call follows violence this week in capital
* Call comes as Tunisia to mark anniversary of uprising
Tunisia's largest union called on Wednesday for a general protest strike next week against the Islamist-led government in an escalation of protests that resulted in violent clashes in the capital this week.
On Tuesday, several hundred Islamists armed with knives and sticks charged a gathering of members of the UGTT union in the capital and broke office windows with stones. Police had to intervene to separate the two groups.
"The UGTT decided to go on strike on December 13, after the attack on the central trade unions and trade unionists on Tuesday," the union said in a statement on Wednesday.
The announcement came as Tunisia prepared to mark the second anniversary of a street peddler's self-immolation on Dec. 17, 2010, that led to a revolution in Tunisia and set the region on the path to uprisings in Egypt, Libya, Yemen, Syria and Bahrain.
UGTT Secretary-General Hussein Abassi accused supporters of the Ennahda party, which leads the government, of being behind the recent clash.
But Rached Ghannouchi, the head of Ennahda, condemned the violence and said some leaders of UGTT wanted to overthrow the government. The headquarters of all national bodies needed to be "emptied of all tools of violence", the party said.
Ennahda came to power following the ousting of former leader Zine al-Abidine Ben Ali, whose police state had repressed Islamists and promoted secularism.
The strike by UGTT, which has 500,000 members, would be the first of its kind in Tunisia since 1984.
Ennahda accused leftists who lost last year's elections of fomenting recent unrest in Siliana, a remote town in the interior, by provoking Tunisians in impoverished areas into confrontations that would drive away foreign investors.
The protests, in which at least 252 people have been injured, including cases of blinding by birdshot, began after a UGTT call to take to the streets to demand jobs, investment and the removal of the Ennahda party 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.