The bloc of West African states on Thursday set coup leaders in Mali a three-day ultimatum to restore constitutional order or face diplomatic and economic isolation. The junta last week chased President Amadou Toumani Toure from power, citing his government\'s \"incompetent\" handling of a rebellion by Tuareg desert warriors in the country\'s north. While the putsch has created turmoil in the capital Bamako, the Tuareg have made territorial gains and the rebel soldiers have earned condemnation from the world community and from African leaders. Five heads of state from the 15-nation regional bloc the Economic Community of West African States (ECOWAS) were on Thursday on a plane headed for Mali for crisis talks with the coup leaders. However, their plane turned back when dozens of pro-coup demonstrators swarmed the runway at Bamako\'s airport. The delegation -- made up of the presidents of Ivory Coast, Burkina Faso, Liberia, Benin and Niger -- returned to the Ivory Coast city Abidjan. At an emergency meeting, they urged ECOWAS member states to place a travel ban on Mali\'s military rulers and threatened a \"diplomatic and financial embargo\" unless order is restored within 72 hours. The grouping had already suspended landlocked Mali on Tuesday and has warned its regional troops are on standby. The European Union, the United States and other Western powers have cut off hundreds of millions of dollars of support to Mali -- except for emergency aid to drought-hit regions. The US State Department voiced disappointment that the African presidents were prevented from landing to mediate a return to democratic rule. \"We support their efforts to achieve a swift return to civilian rule in Mali,\" State Department spokesman Mark Toner said. \"It\'s a disappointment that they weren\'t able to land and actually talk to the mutineers.\" The coup leaders, in a bid to consolidate their power, have unveiled their own constitution. While they promise they will not run in future polls, no date for a return to democracy has been set. Tensions have risen in Bamako, where pro- and anti-coup demonstrators clashed on Thursday. \"There were clashes between the two camps at the labour exchange,\" a Malian security source told AFP, adding that security forces had intervened. \"Three were seriously injured,\" said a source at a Bamako hospital. The coup leaders, who seized power on March 22, voiced anger at the government\'s inability to contain the two-month-old Tuareg rebellion, which has overwhelmed a poorly-equipped military. Many Tuareg recently returned, heavily-equipped and battle-hardened, from Libya where they fought on the side of slain leader Moamer Kadhafi. They have seized several northern towns in fighting that has caused more than 200,000 people to flee their homes in the remote region that is also a key regional hub for weapons and drug trafficking. In the latest clashes, Tuareg fighters attacked the key town of Kidal. \"We are under attack from the rebels... we are fighting back,\" said a Malian soldier in the town on Thursday, speaking on condition of anonymity. He said the Tuaregs\' Azawad National Liberation Movement (MNLA) was attacking from the north while fighters from an allied Islamist group, Ansar Dine (Defenders of Faith), were leading an offensive from the south. The MNLA in mid-January relaunched a decades-old fight for the independence of what the Tuareg consider their homeland. They were joined by renowned rebel Iyad Ag Ghaly who led Mali\'s second Tuareg rebellion since independence from 1990-95 and has returned as the head of Ansar Dine, which has ties to Al Qaeda\'s north African branch. Ag Ghaly once played a key role as power broker between the government and Tuareg and was sent by Toure as an adviser to the consulate in Saudi Arabia. His involvement in recent fighting emerged when a video released in March showed dead and captured soldiers after an attack on the town of Aguelhok, and a spokesman introduces Ansar Dine, naming Ag Ghaly as their commander. Ag Ghaly is seen inspecting fighters and leading them in prayer and the group explains it aims to impose sharia, or Islamic law, in the country. The two fighting parties have ambiguous links, but the MNLA has distanced itself from any religious demands.