* Reasons for latest violence not immediately clear
* Riots are rare in Tunisia
* Two national guard officers in coma - government
* Tunisia preparing for currency convertibility
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TUNIS, Dec 24 (Reuters) - One civilian was killed and several others were injured on Friday when Tunisian police opened fire on protesters during clashes in a provincial city, official and trade union sources said.
An interior ministry spokesperson said police in Bouziane, 240 km (155 miles) south of the capital Tunis, had been forced to "shoot in self-defence" after shots into the air failed to disperse scores of protesters.
Reasons for the latest violence were not immediately clear but clashes broke out a week ago in the town of Sidi Bouzid after a man committed suicide in a protest about unemployment. The protests later spread to several neighbouring cities.
Riots are rare in Tunisia, which has been run for 23 years by President Zine al-Abidine Ben Ali and works closely with Western governments to combat al Qaeda militants.
The North African country has become a regional focus for international financial institutions since announcing a plan to complete current account convertibility of its dinar currency over the 2010-2012 period. [ID:nLDE6A60A4]
In Friday's unrest, rioters barricaded a police station and used molotov cocktails to torch the building and some police cars, the spokesperson said in a statement carried by the official TAP news agency.
One protester was killed and two others wounded in the shooting, the spokesperson added, without saying what caused the clashes. "Numerous members of the (national) guard suffered burn injuries, two of them are in a coma," the spokesperson added.
Mohamed Fadel, leader of the Secondary Education Union, named the dead man. "Mohamed Ammari was killed by a bullet in the chest when police opened fire, while many other protesters were wounded.
"Police have now taken control of the situation ... There is a quasi-curfew in the city," he told Reuters by telephone from Bouziane.
The Tunisian government accused its opponents on Monday of manipulating the clashes at the weekend between police and young people in Sidi Bouzid to discredit the authorities.
Two witnesses told Reuters that rioting resumed late on Monday in Sidi Bouzid, with hundreds of youths confronting police who used tear gas to disperse them. (Reporting by Tarek Amara, Writing by Souhail Karam; Editing by David Stamp)
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