French President Francois Hollande is calling on African leaders to meet in Paris later this week for a summit on how to deal with Boko Haram.
The Islamic extremist group kidnapped more than 300 Nigerian schoolgirls last month in a brazen act of terrorism that has outraged the world.
Hollande proposed the summit on Sunday during a visit to Baku, Azerbaijan.
Some of the girls managed to escape their captors. But Boko Haram is still holding 276. The militants have mocked their parents, threatening to sell the girls on the human trafficking market.
One of the girls who escaped, 19-year-old science student Sarah Lawan, described the armed kidnapping as "too terrifying for words."
She says she is anguished that more of her classmates "could not summon the courage" to escape.
Another victim who fled, a 16-year-old, said men waving AK-47 assault weapons ordered her to cook stolen food before she managed to escape with two other girls.
Pope Francis prayed Sunday for the release of the girls, while British Prime Minister David Cameron called the abduction a part of "violent, extremist Islamism" in Nigeria and elsewhere.
During a television appearance, Cameron held up the "Bring Back Our Girls" sign seen in protests throughout the world.
The United States and several other countries have sent intelligence and military experts to Nigeria to help look for the girls.
U.S. Secretary of Defense Chuck Hagel told ABC television Sunday the United States would do all it could to help, but acknowledged "it will be very difficult." He called Nigeria a "vast country." Hagel said the United States has no plans to send troops to Nigeria.