West African leaders are set to meet to discuss imposing sanctions on Mali, after a deadline they set for mutinous troops to return to barracks expired. Regional group Ecowas had threatened to close borders, freeze assets and withhold credit after troops ousted the government in a coup 10 days ago. Under pressure from Ecowas, coup leader Amadou Sanogo renewed his pledge to cede power, but gave no timeline. Meanwhile, Tuareg rebels now control the north of the country. The rebels, whose ranks have been swelled by fighters returning from the conflict in Libya, encountered no resistance as they seized the strategic city of Timbuktu on Sunday. It is the third northern regional hub to fall in three days. Ivory Coast President Alassane Ouattara, who heads Ecowas, said he had spoken to Capt Sanogo to thank him for his pledge to restore constitutional order. But Mr Ouattara did not say if the sanctions threat remained. "We will work [with other leaders] as soon as possible... so that this [return to constitutional rule] will be done," Mr Ouattara said on Senegalese state television. Mr Ouattara said earlier that the bloc was prepared "to take the necessary measures". Capt Sanogo, who had earlier unveiled a new constitution, on Sunday announced that he would reinstate the 1992 constitution. He said he would consult local political forces to set up a transition body "with the aim of organising peaceful, free, open and democratic elections in which we will not take part". He also told AFP news agency he had despatched envoys to the Timbuktu region to try to obtain a ceasefire with the rebels. His dramatic U-turn came after regional leaders put huge pressure on the junta. Ecowas leaders are due to meet in the Senegalese capital Dakar on Monday and discuss Mali on the sidelines of the swearing-in of Senegal's new President, Macky Sall. The group's 72-hour deadline for Malian troops to stand down expired on Monday. The government's handling of the fight against the Tuareg rebels had been the main grievance of the soldiers. But since they ousted President Amadou Toumani Toure, they have lost huge swathes of territory. Witnesses in Timbuktu said rebel fighters had taken the airport, administrative buildings and military camps. "The city is totally under their control," city Mayor Ousmane Halle told AP news agency by phone. Residents told the BBC that there had been no fighting in the town. "Early in the morning there were some noises, and people were scared. And then later on there's no fighting on the streets, nothing happened they just fired in the air and finished," said one resident contacted by telephone. Witnesses said rebel fighters were mixing with local Arab militiamen, who have been protecting businesses since troops fled the town. Rebels from the National Movement for the Liberation of Azawad (MNLA) are said to have been driving around the town in pick-up trucks, waving the MNLA flag. The rebels, who want an independent Tuareg homeland, are reported to be backed by Islamist fighters. A statement released by the MNLA said they would now begin their "mission of defending and securing the territory of the Azawad, for the happiness of its people". Azawad is the rebels' term for the entire north of Mali. Two other important northern centres, Kidal and Gao, fell to the Tuareg fighters in recent days.