Security forces and hardline Islamists fought street battles in Tunis on Sunday, with one protester killed and 15 policemen wounded, after the authorities banned the Salafists from staging their annual congress.
The confrontations infuriated moderate Islamist Prime Minister Ali Larayedh, who for the first time linked the Salafist Ansar al-Sharia group which is considered close to Al-Qaeda to "terrorism".
"Ansar al-Sharia is an illegal organisation which defies and provokes state authority," Larayedh told Tunisian state television during a visit to Qatar.
"It has ties to and is involved in terrorism," he said.
Sunday's fighting erupted when Ansar al-Sharia (Partisans of Islamic Law) urged its followers to mass in the capital's suburb of Ettadhamen in defiance of a ban on their gathering in the central city of Kairouan.
Salafists advocate an ultra-conservative brand of Sunni Islam, and Ansar al-Sharia, whose fugitive leader fought with Al-Qaeda in Afghanistan, does not recognise the authority of the Tunisian state.
Suppressed under president Zine El Abidine Ben Ali, radical Islamists have grown increasingly assertive since the popular uprising that ousted the secular strongman in January 2011.
Islamists have been blamed for a wave of violence that has rocked the North African country, including an attack on the US embassy last September that left four assailants dead and bombings targeting shrines venerated by Sufis who follow a mystical form of Islam.
Hundreds of Salafists erected barricades in the streets of Ettadhamen, a poor neighbourhood 15 kilometres (9 miles) west of Tunis, and hurled rocks at police who responded with tear gas, an AFP journalist reported.
The security forces used armoured cars and bulldozers to destroy the barricades and gain access to Ettadhamen, a stronghold of the Salafist group.
Police closed in on the Islamists, forcing them to retreat to the neighbouring district of Intilaka where sporadic clashes continued into the early evening.
A hospital official said one protester died of gunshot wounds and the interior ministry late Sunday confirmed the death and updated the toll of wounded.
"Fifteen policemen have been wounded, three seriously including one in intensive care. Three protesters were wounded and one is dead," said interior ministry spokesman Mohamed Ali Aroui.
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Mounira Ben Ghazi, a senior supervisor at Mongi Slim hospital, named the dead man as Moez Dahmani, in comments made to Express-FM radio station.
Police detained several Salafists including Ansar al-Sharia spokesman Seifeddine Rais, a police source and the movement said.
Rais said last week that the group did not need "permission from the government to preach the word of God" and warned that the authorities would be held responsible for any bloodshed.
Ansar al-Sharia had planned to hold its congress in Kairouan, the country's religious capital, but the government banned the meeting, saying it posed "a threat to public order".
The group nevertheless tried to muster support for the meeting in Kairouan, where its followers shouted insults at the police deployed in the city and clashed briefly with security forces who fired tear gas at them.
Tunisia's ruling Islamist party Ennahda, a moderate group criticised for being too lenient towards the Salafists, has hardened its stance towards the extremists in recent months.
In early May, the government said its forces were pursuing two groups in the western region bordering Algeria who are linked to Al-Qaeda.
One resident of Ettadhamen said hundreds of Ansar al-Sharia supporters poured into the district after the group was prevented from meeting in Kairouan.
Some were armed with sticks and knives and waving the black flag of the movement.
A top Al-Qaeda chief urged Tunisia's Salafists to ignore government provocation in order not to lose public support, the US-based SITE monitoring service said on Sunday.
"Don't you ever be provoked by the regime and its barbarism to do rash acts that might spoil your blessed popular embrace," Abu Yahya al-Shanqiti, a member of Al-Qaeda in the Islamic Maghreb's sharia committee, was quoted as saying.
"Be wise and patient," he added in a message of support for Ansar al-Sharia.
Ansar al-Sharia's fugitive leader, Saif Allah Bin Hussein, a former Al-Qaeda fighter in Afghanistan, warned earlier this month that he would wage war against the government, accusing it of policies in breach of Islam.