The United States and France are backing moves to muster an African-led intervention force to smash the jihadist stronghold in northern Mali, and one of the main objectives is to eradicate the kidnapping of Westerners for ransom.

Western officials say al-Qaida in the Islamic Maghreb, the main jihadist group in North Africa, may seek to seize more hostages as the Islamists face an offensive against them.

Kidnapping is the main source of revenue for AQIM, the primary jihadist force that has held the vast desert region since March. It has roughly $3 million in ransom for every captive it's released. AQIM is believed to be holding six French citizens, three other Europeans and three Algerian diplomats.

Its pickings have got a lot slimmer since the jihadists hijacked northern Mali from Tuareg separatists who took control of the region in the fallout from the 2011 Libyan civil war. Fewer foreigners are moving through the region, previously a well-traveled adventure tourism spot, and this has limited AQIM's revenue-earning capabilities.

AQIM is thought to be using up its ransom money to buy weapons and ammunition as it builds up defenses to counter expected military intervention led by regional states that see the jihadist sanctuary in Mali as a major security threat.

That could mean the Islamists will try to carry out more kidnappings to top off their depleted war chest.

David Cohen, U.S. Treasury undersecretary for terrorism and financial intelligence, estimates the al-Qaida network as a whole has "collected approximately $120 million in ransom payments over the past eight years.

"AQIM ... has likely profited most from kidnapping for ransom, or KFR," he told a security conference at London's Royal Institute of International Affairs Oct. 5.

The U.S. global intelligence consultancy Stratfor estimates AQIM has raked in as much as $89 million since 2003.

Where the average ransom was once around $3 million, it's now pegged at $5 million per captive in some cases.

Cohen said AQIM reportedly demanded $70 million for the release of four French hostages who were seized in Niger in September 2010.

AQIM's "most recent payout was about $19.4 million, received in mid-July in exchange for the release of three aid workers -- two Spaniards and one Italian -- kidnapped in Tindouf, Algeria, in October 2011," Stratfor noted.

Al-Qaida central, the badly battered core leadership holed up in northern Pakistan, can no longer provide for funds for its various branches.

But, Cohen observed, "ransom money is supporting the expansion of AQIM's influence and control in northern Mali, which it is using as an active area of operations as well as a safe haven."

Security analysts estimate AQIM was until recently spending around $2 million of its ransom money every month to supports its operations.

"If this trend were to continue, AQIM ordinarily would not need to compel its next ransom payout until around May 2013," Stratfor observed.

"However, due to increased counter-terrorism operations against it, the jihadist group will likely increase its defensive measures, which will necessitate an uptick in revenue.

"Taking hostages ... will likely occur more frequently as the group attempts to raise more funds."

AQIM has carried out around 20 kidnapping operations in the Maghreb, the Arabic word for North Africa, and the Sahel, the semi-arid belt that runs across Africa from the Atlantic to the Red Sea, since February 2003.

Initially these ran at one a year, often involving multiple hostages, but since 2007 there have been three to five raids a year. All captives have wound up in northern Mali.

Stratfor estimates AQIM "may currently have about $16 million left from its July ransom which -- under normal circumstances -- could last until next May.

"However, it's now likely spending it a higher rate than usual to acquire guns, ammunition and manpower as it faces the threat of being targeted by the Malian army, a proposed West African peacekeeping force and U.S. and French counter-terrorism operations in the region."

Meantime, the U.S. administration is seeking to develop a unified strategy with European powers to counter the kidnappings. The Americans don't pay ransoms, but some European governments have done so.

Cohen visited Britain, France, Germany and Italy during a weeklong tour of Europe in October but it's not known if this convinced the Europeans to line up with the Americans.