BAMAKO - Islamist fighters killed 10 Tuareg rebels in two attacks near northern Mali's border with Algeria this week in a growing wave of violence, Tuareg officials said on Saturday.Six fighters from the National Movement for the Liberation of Azawad, northern Mali's largest Tuareg rebel group, were killed on Thursday when Islamist militants attacked their checkpoint in the town of Talahandak, the group said.It added that Islamist fighters were also killed in the clashes, though it did not give further details.Four more died on Friday when a convoy of reinforcements was ambushed on its way to the border, said Sidi Ould Ibrahim Sidat, an official with the Tuareg umbrella group, the Coordination of Movements of Azawad.This organization signed a peace deal in June with the Malian government as part of efforts to draw a line under a series of separatist uprisings.He blamed the attacks on fighters from al Qaeda in the Islamic Maghreb (AQIM), the Movement for Unity and Jihad in West Africa (MUJWA), Ansar Dine and the Macina Liberation Front."The attacks were caused by Islamists ... that are opposed to the peace deal," Sidat said. "AQIM, MUJWA and Ansar Dine have even met to put in place a coalition."Islamist groups hijacked a Tuareg rebellion in early 2012 to seize Mali's desert north. A French-led intervention scattered them a year later, but Islamist fighters have stepped up attacks this year.Nineteen people, most of them foreigners, were killed in an assault on a luxury hotel in the capital Bamako in November. Islamist groups AQIM, al Mourabitoun, and the Macina Liberation Front all claimed responsibility for the attack.