Tunisi. Tunisian security forces have killed two fighters from the Ansar al-Sharia group and arrested two others in a Tunis suburb, according to the North African nation’s Interior Ministry.The two men arrested, Mohamed Khiari and Mohamed Aouadi, are leaders of Ansar al-Sharia’s military wing and are implicated in the assassination of opposition legislators Chokri Belaid and Mohamed Brahmi, a ministry source said on Monday.The killings and arrests came during a sweep in a northern suburb of Tunis by an anti-terrorism squad, the source told AFP.The fighters died after a heavy exchange of fire, the ministry said in a statement, naming just one of the deceased, Adel Saidi.Since the 2011 revolution that overthrew Zine El Abidine Ben Ali, Tunisia has been rocked by waves of violence blamed on armed groups that were repressed earlier.Ali Larayedh, prime minister, last month linked Ansar al-Sharia, the largest such movement in Tunisia, with al-Qaeda in the Islamic Maghreb, and accused it of carrying out the worst "terrorist” attacks since the uprising.The group is also believed to be supporting fighters holed up in the remote Mount Chaambi region, along the Algerian border, who have been hunted for months by the Tunisian army.Ansar al-Sharia insists it has no ties with foreign groups, while expressing its "loyalty to the principles of jihad and to jihadist groups around the world”.Larayedh’s Islamist Ennahda party, which heads the coalition government, has been heavily criticised by secular political parties for not doing enough to prevent the violence that has plagued the country.It also faces accusations of mismanaging the economy and failing to improve living standards, which were crucial grievances of many who participated in the mass uprising that toppled Ben Ali.In recent months, following growing calls for action from opposition parties and civil society groups, the government has taken a much tougher stand towards armed groups, and Ansar al-Sharia in particular.The assassination in a street of Brahmi on July 25, less than six months after Belaid was killed in similar circumstances, plunged the country into fresh political turmoil.Thousands rallied in Tunis on Saturday to mark 40 days since Brahmi’s murder and to call for the ruling coalition to step down.