Ecowas, the West African economic bloc, has given Mali's junta leaders 72 hours to restore the constitution, or else face sanctions.
The proposed sanctions include sealing all land borders and freezing Mali's assets, the BBC reported.
The Associated Press said that closing Mali's borders would also cut off its supply of gasoline.
West African leaders met in Ivory Coast on Thursday after abandoning plans to meet with junta leaders in Bamako, the Malian capital.
Five African presidents, from Ivory Coast, Benin, Liberia, Niger and Burkina Faso, were on a plane due to arrive at Bamako airport. But instead the plane turned around for security reasons, because pro-junta demonstrators had taken over the tarmac.
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Commission president for Ecowas Kadre Desire Ouedraogo told reporters that if the 72-hour deadline was not met, all 15 countries of the regional bloc would deny Mali access to their ports, and halt transfers to banks in Mali from the regional central bank, the BBC said. Ecowas has already put a peacekeeping force on standby.
The AP reported that several thousand people rallied this week in support of the junta, indicating a broader frustration with deposed President Amadou Toumani Toure.
While the political crisis deepened in the capital, also on Thursday ethnic Tuareg separatists attacked the key town of Kidal, in northern Mali, Agence France-Presse reported.
Renegade soldiers in Mali, frustrated over their government's handling of the Tuareg rebellion in the north, seized control of the country on March 22. The coup happened one month before Mali's presidential election, in which the democratically elected Toure is due to step down.
Toure told AFP this week that he is safe in Bamako and is not being held captive by the military junta.
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