Malian soldiers fired at Islamist fighters who tried to push toward the government-controlled south of the country Tuesday.
Military sources say soldiers fired "warning shots" overnight to halt the advance of fighters toward Mopti, a government stronghold about 650 kilometers northeast of the capital, Bamako.
The French news agency, AFP, says the fighters retreated after the shots.
The incident raised fears of new clashes in Mali, where Islamists and Tuareg separatists took control of the north after renegade soldiers overthrew the government in Bamako in March. The Islamists have seized full control of the region.
The government and some of the rebel groups are tentatively set to hold peace talks in neighboring Burkina Faso on Thursday.
African Union chief Boni Yayi, the president of Benin, is calling on NATO to play a part in an AU-led peacekeeping force in Mali. Yayi said after talks in Ottawa with Canadian Prime Minister Stephen Harper Tuesday that the situation in Mali is an international question. There are fears the Islamists could use northern Mali as a center for plotting terrorism.
Prime Minster Harper said Canada will only send humanitarian aid.
The United Nations Security Council has approved a plan for the Economic Community of West African States to deploy at least 3,000 troops to Mali to help retrain the army and recapture the north. No military operation is expected until later this year.
In Washington, State Department spokeswoman Victoria Nuland said the United States is closely monitoring developments between the government and Islamists.
In late December, Islamist group Ansar Dine and the Tuareg separatist group MNLA agreed to a cease-fire with the government. Ansar Dine, however, suspended its cease-fire last week, saying the government was not sincere about peace negotiations.