West African leaders Saturday called for greater international involvement in Mali as they met to speed up the deployment of regional troops to boost a French-backed offensive to halt an Islamist onslaught.

The emergency summit in Ivory Coast's main city Abidjan was also attended by French Foreign Minister Laurent Fabius who clearly said it was time for the Africans to take over and "as soon as possible", adding that this was "the aim of our meeting."

The White House and the U.S. Defense Department are at odds over the danger posed by radical Islamic groups that have taken control of parts of Mali and are stirring up trouble in other parts of West Africa, The Los Angeles Times reported late Friday.

Citing unnamed U.S. officials, the newspaper said the events in Mali and neighboring Algeria have prompted sharp debate within President Barack Obama's administration over whether these radicals present enough of a risk to warrant a military response.

Algerian special forces have freed nearly 650 hostages from Islamist gunmen at a remote gas plant near the Libyan border, but some 60 foreigners are still missing, national media said on Friday.

"Nearly 650 hostages seized in the attack carried out on Wednesday by a terrorist group... among them 573 Algerians and more than half of the 132 foreign hostages, were freed" by Algerian special forces, the APS news agency reported.

The brother of al-Qaida chief Ayman al-Zawahiri joined dozens of Egyptian Islamists in a protest Friday near the French embassy in Cairo against French intervention in Mali.

Mohammed al-Zawahiri took part in the demonstration during which protesters accused Paris of being "at war against Islam".

French Foreign Minister Laurent Fabius said he would attend an emergency summit of the west African bloc ECOWAS on Saturday to help accelerate the deployment of an African military force in Mali.

"I will go there with a military attache and we will see with our African friends how we can speed up the deployment of MISMA (the International Mission for Mali Assistance)," he told AFP.

Islamists who held several hostages at an Algerian gas plant sparking a bloody commando raid threatened Friday to stage more attacks, according to a spokesman cited by the Mauritanian news agency.

"Taking into account the suffering of the Algerian people, we promise the regime in place that there will be more operations," a spokesman for the "Signatories in Blood" told ANI.

French-backed Malian troops Friday wrested two key central towns from Islamist rebels as hostage-takers in neighboring Algeria said they wanted to negotiate an end to France's military intervention.

As the dramatic hostage siege unfolded in Algeria -- where extremists took hundreds captive in a gas field to retaliate for the week-old French operation in Mali, sparking a deadly commando raid -- fighting has continued unabated on the ground in Mali.

Algeria came under mounting international criticism on Friday as fears grew for dozens of foreign hostages still unaccounted for after a deadly commando raid against their Islamist captors at a desert gas field.

Algerian Communications Minister Mohamed Said said Thursday's air and ground assault freed a "large number" of hostages, but Algerian news reports said nearly 600 of those rescued were Algerian workers but just a handful were among the 41 foreigners reported seized.

Washington was Thursday trying to determine the fate of U.S. hostages caught in the crossfire of an Algerian military rescue bid, and urged its embassies and U.S. businesses to tighten security.

"We are certainly concerned about reports of loss of life. And are seeking clarity from the government of Algeria," White House spokesman Jay Carney said.

Some of France's EU partners are considering whether to offer troops to back up its military campaign in Mali against Islamist insurgents, French Foreign Minister Laurent Fabius said Thursday.

After emergency EU talks on Mali, Fabius said all had "expressed their solidarity with Mali and support for France's action" and some were mulling "an offer of troops," although "we won't force anyone."