Already, the armed groups' activity and a pervasive drought have displaced hundreds of thousands of Malians.
And the Islamists' movement southward has raised concerns among leaders in West Africa and elsewhere, some of them calling for swift and decisive military intervention in support of Mali's government, based in Bamako.
The Economic Community of West African States plans to hold an emergency meeting in Abidjan, Ivory Coast, to prepare to send troops to Mali to help government forces, a spokesman for the organization said.
West African troops are expected to number 3,500 and will operate in the framework of the United Nations resolutions, ECOWAS spokesman Sunny Ugoh said.
The U.N. Security Council last month authorized a one-year military peacekeeping mission in the country. ECOWAS members pledged thousands of troops, and the Security Council has urged other nations to contribute forces as well.
French officials earlier expressed reluctance to send troops to Mali, amid a broader vow to scale back their military involvement in Africa. So the decision to get involved in Mali -- a mission French President Francois Hollande said "will last as long as necessary" -- underscores how concerned they are about the situation there.
French hostages have been taken in neighboring Niger by al Qaeda in the Islamic Maghreb, and Paris appears intent on containing any further militant expansion in the heart of Africa.
On Sunday, a Twitter post from the office of Mali's president said Canada, Britain and the United States agreed to provide logistical support.
British Prime Minister David Cameron agreed to "provide logistical military assistance to help transport foreign troops and equipment quickly to Mali," but no British personnel in a combat role, a Downing Street spokesman said.
The U.S. military is weighing options, including logistical support and intelligence sharing with France, a U.S. defense official, who spoke on condition of anonymity because no decisions have been made, said Saturday.
"This is a serious issue, and ... the United States is committed to going after terrorists wherever they may be in order to protect American interests, but also those of our partners and allies around the world," Pentagon spokesman George Little said last week.