Mali risks descending into "catastrophic" violence, the UN rights chief has warned, after a string of attacks by Islamist rebels increased the pressure on French-led forces in the west African nation. After four days of suicide bombings and guerrilla fighting in the northern city of Gao, fears of fresh attacks were high following a call from Al-Qaeda in the Arabian Peninsula (AQAP) for a holy war. UN rights chief Navi Pillay warned against reprisal attacks by the Malian army and black majority on light-skinned Tuaregs and Arabs accused of supporting the Islamist rebels. "As the situation evolves, attacks and reprisals risk driving Mali into a catastrophic spiral of violence," Pillay told the UN Security Council on Tuesday. "Protection of human rights is key to stabilising the situation," she added. Rights campaigners have accused Malian troops of killing suspected rebel supporters and dumping their bodies in wells. Some black Malians have turned on their Tuareg and Arab neighbours in northern towns recaptured from the Islamists. And in Timbuktu last week, a grave containing several Arabs' bodies was discovered. Many Arabs and Tuaregs have already fled the north, fearing reprisals. A total of 377,000 people have fled their homes, including 150,000 who have sought refuge across Mali's borders, according to the UN. Mali imploded after a coup on March 22 last year by soldiers who blamed the government for the army's humiliation at the hands of north African Tuareg rebels, who have long complained of being marginalised by Bamako. With the capital in disarray, Al-Qaeda-linked fighters hijacked the Tuareg rebellion and took control of the north. Analysts say the crisis has been fuelled by a complex interplay of internal tensions and international factors, including Al-Qaeda's call to global jihad. Those concerns were underlined Tuesday when AQAP, Al-Qaeda's Yemen-based branch, condemned France's intervention as a "Crusader campaign against Islam" and called all Muslims to join a holy war against it. Around 90 percent of Malians are Muslim, but the Islamist extremists' hardline ideology is not broadly accepted. "Supporting the Muslims in Mali is a duty for every capable Muslim with life and money, everyone according to their ability," AQAP's sharia committee said in a statement reported by the US-based SITE Intelligence agency. AQAP -- which US officials have labelled Al-Qaeda's most dangerous franchise -- said jihad is "more obligatory on the people who are closer" to the fight and that "helping the disbelievers against Muslims in any form is apostasy". That was an apparent reference to north African countries, notably Algeria, which agreed to let French warplanes use Algerian airspace. Islamist gunmen subsequently attacked a gas field there, unleashing a hostage crisis that left 37 foreigners dead. Al-Qaeda in the Islamic Maghreb, Al-Qaeda's north African branch, is one of the groups that seized control of northern Mali for 10 months after the March coup, along with the Movement for Oneness and Jihad in West Africa (MUJAO) and Ansar Dine (Defenders of the Faith). Canada's Foreign Affairs Minister John Baird echoed the fears of many observers Tuesday when he made it clear that Canada would not send troops to a peacekeeping mission. "We're not, at the drop of a hat, going to get into another Afghanistan in this region," he told lawmakers. But requests for financial assistance and military trainers are being considered. France launched its intervention on January 11, after Mali's interim government called for help fending off the Islamist insurgents as they advanced into southern territory. After pushing the rebels from the towns under their control, France is eager to wind down the operation and hand over to United Nations peacekeepers. Gao, the largest city in the north, has been hit by suicide bombings and street battles in recent days. On Tuesday, troops from Mali and Niger were patrolling the nearly empty streets, brusquely interrogating the few people they encountered. The European Union said it would resume aid to Mali worth up to 250 million euros ($336 million) that was suspended after the coup.