KAIROUAN, TUNISIA // The Great Mosque at Kairouan is an austere building in yellow brick, which has stood since the dawn of Islam and seen Islamic empires of all strands rise and fall around it.
Last year, in the shadow of its imposing minaret, thousands of supporters of Tunisia's main radical Islamist movement, Ansar Al Sharia, gathered for an annual congress, led by the one-time fighter in Afghanistan known as Abu Iyadh.
The priorities laid out in the speeches were relatively uncontroversial - Islamically correct tourism and charitable programmes were called for.
It was the second annual congress after the fall of president Zine El Abidine Ben Ali in 2011, and the beginning of new political freedoms.
This year was different. The congress was banned by the authorities. Outside the mosque were no jubilant crowds of men waving the black flag of militant Islam. Instead there were armed plain-clothed and uniformed police, a dozen sniffer dogs and the whiff of tear gas in the air from nearby altercations between police and local youths. In the suburbs around the capital, where the group organised a small rally, one man died in clashes with security forces.
Tunisia's government, led by the moderate Islamist Ennahda party, was once accused of conciliation to the country's substantial minority of militants with a violent interpretation of their faith. Now, in a series of statements and actions, the government seems to have decided to crack down on the groups, amid what western and regional officials say are growing security threats.
"The government will deal with Ansar Al Sharia as an illegal organisation that has committed acts of violence and has ties to terrorism," said Ali Larayedh, the prime minister, this week. "The head of this movement is involved in many affairs, including terrorism, and is wanted by security forces."
A war of words between the authorities and the radicals flared up earlier this month.
Ministers initially said they were undecided as to whether to allow the annual congress to go ahead, and later stated that the meeting was forbidden, as Ansar Al Sharia is not a registered association and had not applied for the necessary permission to hold an event expected to attract thousands of people.
A response that Abu Iyadh, whose real name is Saifullah Ben Hassine, posted on his Facebook page apparently addressed Ennahda as "tyrants" who have nothing to do with Islam.
"You are fighting a victorious religion helped by Allah and no force on Earth, no matter how strong, can defeat it," he said.
He reminded the government that members of the group had fought alongside other radical Muslim groups from Iraq to Chechnya and "will never hesitate to sacrifice for their religion in Tunisia".
The threat and the reference to the government, which is technically an interim body, as "tyrants" is a significant escalation in rhetoric and comes at a time when the group may be growing its capacity for violent activity.
Ansar Al Sharia is thought to be the driving force behind encouraging and facilitating the flow of Tunisian fighters to Syria and Mali.
One western diplomat said earlier this year that the group has been the dominant force in sending 3,000 Tunisian fighters who are believed to be in fighting alongside Islamist rebels in Syria, and about 500 who fought in Mali against a French-led offensive earlier this year.
A fear frequently expressed by politicians and analysts that such fighters could return and operate on Tunisian soil was fuelled last month when it became clear that the Mount Chaambi area bordering Algeria was scattered with landmines. Several soldiers were gravely wounded by the home-made devices, which Tunisian authorities said were laid by Tunisian and Algerian militants returning from Mali.
Ennahda's leader, Rachid Ghannouchi, explicitly linked Ansar Al Sharia with the minefield in a speech earlier this month.
Adding to fears about the group's increased militancy is a change in rhetoric from the regional branch of Al Qaeda. In October last year, a statement from Al Qaeda in the Islamic Maghreb seemed ready to coax Ennahda, rather than confront them. It advised the party to abolish an unpopular "anti-terror" law passed by Ben Ali, under which many Islamists were detained.
But last week the group, which refers to Ansar Al Sharia as brothers, showed a sharp change in tone, referring to "a conflict between the good and the evil people, between the callers to the Sharia of Allah and his party and the callers to the way of Satan and his followers".
Over the past week, as the banned meeting approached, the government and Ansar Al Sharia, whose supporters are now thought to number in the tens of thousands, refused to back down.
Spokesmen from the group insisted that the congress was not cancelled, and posted videos online of how to sneak past police into Kairouan.
The former justice minister, Nourredine Bhiri, who is still a prominent Ennahda member, insisted, after meetings in Kairouan, that "every party that does not respect the law will be punished".
When Sunday came, amid heavy security in Kairouan, the congress did not take place. Men who adopted the beards and Afghan-style clothing of Salafis were turned back on the roads. About 200 were arrested, the prime minister tsaid , and a rally organised in Ettadhamen suburb of Tunis prompted fierce clashes, in which one person was killed.
If it proceeds with this crackdown, the government will likely have the support of many people who find the ascetic and aggressive nature of Ansar Al Sharia frightening and un-Tunisian.
"Ansar Al Sharia are extremist. They cause threats to society because they see themselves as right and all those who oppose them as wrong," said Taieb Ghozzi, the imam at the Great Mosque in Kairouan. "It's better to ban their congress."
However, the government will steer a difficult path in using police to quell an Islamist foe. Under Ben Ali, laws ostensibly designed to combat terrorism were used to detain people who were non-violent Muslims or political Islamists. The police were often accused of brutality.
For some people, Ennahda's new tactics are uncomfortably similar. In Kairouan, clashes on Sunday were not led by Ansar Al Sharia but by ordinary young men who said they resented the heavy police presence in the town.
"This is a revolution against the police and the politics," said Ahmed Dhoubi, a 23-year-old student, one of a throng facing off against police. "It's a revolution for Islam and for the quality of life."
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