Bamako - Africa's Sahel region risks becoming a "space for terrorists" unless immediate, co-ordinated action is taken, Chad's President Idriss Deby warned on Monday, as the area's leaders gathered for security talks in the Malian capital.The presidents of Chad, Burkina Faso, Mali, Mauritania and Niger met in Bamako to discuss the region's perilous security situation, where attacks mounted by jihadists and armed groups are on the rise and increasingly targeting civilians."We have witnessed these last few months a multiplication in terrorist attacks in the Sahel. These attacks remind us of the urgency of our fight," Deby said in his role as chief of the so-called "G5" group of nations.The threat posed by these groups was "not only real but taking on new proportions," the longtime Chadian leader said. "If we do not act quickly our zone will become a space for terrorists."Around 3 500 French troops are currently stationed in the Sahel with a mandate to secure the vast, largely desert area in the face of an increasingly nimble array of Islamist groups, some aligned with Al-Qaeda."We need to co-ordinate our efforts to rise up to the challenge," said Malian President Ibrahim Boubacar Keita, whose nation has struggled with jihadists using its northern region as a launching pad for attacks.The leaders' words echo fears among the intelligence community that jihadists could mount more attacks like the ones carried out in three other west African nations but planned in Mali since January last year.Northern Mali was described as a "known hideout for terrorists" in an internal G5 document seen by AFP.Mali itself is frequently hit: more than 70 people died in a suicide bombing in Mali on January 18, targeting militia groups committed to restoring peace in the African country, the worst such attack in years.Chad and Niger are currently battling Nigerian Islamist group Boko Haram, while jihadists struck a hotel in the capital of Burkina Faso in January 2016.Mauritania was once plagued by Islamist attacks within its borders, but has made significant security gains.