PARIS: France and the United States are on a diplomatic offensive to secure vital Algerian backing for a military intervention in Mali, where Islamist militia are tightening their grip on the north every day.
Algeria is the region's biggest military power by some margin and has been dealing with northern Mali's top Islamist leaders -- most of them are Algerian -- for years.
"An intervention in northern Mali is possible without the military backing of Algeria but not without its green light," said Pierre Boilley, the head of the Centre of African Studies, a French think-tank.
France, the former colonial master of both countries, discussed the crisis that has split Mali in two since March during a visit by Foreign Minister Laurent Fabius in July.
Mali will again top the agenda when US Secretary of State Hillary Clinton meets President Abdelaziz Bouteflika in Algiers on Tuesday.
French President Francois Hollande is expected there in December.
Once considered one of Africa's most promising democracies, Mali has slid into chaos this year.
Renegade soldiers overthrew the government of president Amadou Toumani Toure on March 22.
The coup was short-lived but a Tuareg rebellion that had launched a major offensive two months earlier took advantage of the power vacuum to seize the entire northern half of the country.
The main secular Tuareg group was soon overpowered by Islamist groups with ties to Al Qaeda in the Islamic Maghreb (AQIM), itself an evolution of a fundamentalist movement involved in Algeria's bloody civil war.
The Islamists, who have been enforcing an extreme form of Islamic law in recent months, have access to the huge supply of Libyan weapons that flooded the region after Moamer Kadhafi's demise, heightening fears northern Mali could become what Afghanistan was to the Taliban a decade ago.
Experts say Algeria's huge foreign exchange reserves, its experience in tackling a decades-long Islamist insurgency and the 1,400-kilometre (870-mile-) and largely porous border it shares with Mali, give it a crucial role in any intervention.
Algeria, home to some 50,000 Tuaregs, had initially opposed plans for an international military force to wrest back Mali's north, largely due to fears it could spark unrest at home.
It has since slightly softened its stance saying that while talks are essential it would not necessarily oppose a military intervention.
The UN Security Council on October 12 approved a resolution urging West African nations to speed up preparations for an international military force of up to 3,000 troops that would attempt to reconquer northern Mali.
France and the United States have offered logistical support.
"Algeria has the capacity to scupper any intervention by not sealing the border hermetically," said Alain Antil, a researcher at the French Institute of International Affairs.
"The approach on Mali must go beyond (West African regional bloc) ECOWAS and must include Algeria," said Richard Downie, deputy director and fellow with the Washington think-tank Center for Strategic and International Studies (CSIS) Africa programme.
According to analysts, Algeria wants to contain the risk posed by AQIM in northern Mali but fears that military involvement could backfire.
"After having succeeded in tackling the menace of terrorism, Algeria does not want to become the main target of these movements," said French terrorism expert Jean-Charles Brisard.
US officials have meanwhile stepped up calls for greater regional involvement.
"We encourage greater cooperation with the regional states in dealing with terrorist threat," Johnnie Carson, Assistant Secretary of State for the Bureau of African Affairs, told AFP.
"We encourage collaboration, communication with the notion that terrorists don't recognise international boundaries... That is the key to success".
Pierre Boilley said Algiers had in recent weeks invited high-ranking delegations of the Ansar Dine Islamist group -- which controls the Malian city of Timbuktu -- to convince it to sever ties with AQIM.
"Many countries in the region such as Algeria and several analysts think that negotiations are possible with Ansar Dine. Let us see," Jean Felix-Paganon, France's envoy to the Sahel, told Jeune Afrique weekly.