Al-Qaeda-linked radical Islamists in northern Mali have enlisted new fighters from a tribal militia to strengthen their grip on the region, according to a witness and the group. A resident of Douentza town told The Associated Press on Sunday that some 400 combatants of the government-backed Gandakoy militia appear to have broken ranks and joined the Islamists, bolstering the radicals\' edge over ethnic Tuareg rebels in the area. The witness, reached by phone from Bamako, declined to be named for fear of reprisals by the Islamists of the Ansar Dine group. One of the group\'s Timbuktu-based fighters, Oumar Ould Hamaha, confirmed the resident\'s observation, saying the Gandakoy militants in in Douentza are \"100 percent with Ansar Dine.\" After a coup that ousted Mali\'s democratic government in March, ethnic Tuareg rebels seeking secession took control of the country\'s north - an area larger than France - but were driven out in June by the Islamists vowing to introduce an ultra-strict interpretation of Islamic law, the Shariah. They are estimated to number about 700 fighters, but exact figures are not available. Douentza, some 250 kilometers (150 miles) south of Timbuktu, is considered to lie on the front line between Mali\'s army and the separatist Tuareg rebels of the National Movement for the Liberation of the Azawad. Ansar Dine\'s spokesman, Sanda Abou Mohamed, also confirmed that the Gandakoy \"who respect our principles\" arrived in Douentza. \"I can\'t tell you the exact number of Gandakoy fighters in Douentza,\" he said, adding that they are there to control one of the important roads linking the country\'s south and north. In Goundam town, some 100 kilometers west of Timbuktu, the Islamists briefly detained some 90 protesters and whipped them in an apparent attempt to intimidate the locals following a demonstration against them on Friday, according to residents. In a sign that eerily reminded the international community of the Taliban\'s destruction of famous ancient Buddha statues in Afghanistan in the 1990s, the Islamists have also started to destroy Muslim shrines and historical sites, including some in Timbuktu which are part of a UNESCO World Heritage Site.