Some 1,600 French troops are struggling to disarm militia fighters in the violence-torn Central African Republic as they run into heavier resistance than they expected in the former French colony.

There are indications that the French force, already beefed up from the original strength of 1,200 announced last week, might not be large enough to pacify the entire country that's been gripped by largely Muslim-Christian bloodletting for weeks.

Even with some 3,000 African Union peacekeepers, who like the French are concentrated around the riverside capital, Bangui, the intervention force has limited capabilities even with the support of French air force Rafale fighter jets based in neighboring Chad, another former French colony, and helicopters stationed at French bases across Africa.

"French forces ... will be more active in securing select population centers than they had been willing to be in the past, but it is still unlikely that they will rid the country of rebels," observed the U.S. global security consultancy Stratfor.

The French force suffered its first casualties in Operation Sangaris -- named after a local butterfly -- Monday with two marine infantry paratroopers fatally wounded in a night-time skirmish with gunmen near Bangui's airport.

But the French military spokesman, Col. Gilles Jaron, said Tuesday the troops had begun disarming former rebels and militias who have clashed repeatedly in recent weeks, spreading terror among the poverty-stricken country's 4.6 million people.

The violence began in March, when five Muslim rebel groups joined forces in a coalition known as Seleka and toppled the government of Christian President Francois Bozize, who fled the country.

The Seleka leader, Michel Djotodia, took over the presidency, the first Muslim to rule the predominantly Christian country since independence from France in 1960.

Although Djotodia disbanded the Seleka, many militiamen went rogue and he lost control of them. Warlords imposed a reign of terror across much of the country, burning villages, killing indiscriminately and engaging in mass rapes.

Christians formed their own vigilante "self-defense groups" as central authority, never strong, collapsed altogether amid the widening Christian-Muslim atrocities.

Some 400 people were killed in several days of frenzied bloodletting in Bangui alone before the French began deploying last week.

The deployment accelerated after the U.N. Security Council authorized the intervention to restore order "by all necessary measures."

French President Francois Hollande, who flew to Bangui Tuesday after attending the memorial service for Nelson Mandela in South Africa, has said Djotodia should step down or be replaced.

"I don't want to point fingers, but we cannot keep in place a president who was not able to do anything, or worse, let things happen," Hollande declared. "The idea is to head as fast as possible toward elections. "

Hollande's intervention in the Central African Republic marks France's second military excursion into its former colonial empire in Africa this year.

In January, he sent a 1,400-man task force into northern Mali to drive out jihadist forces linked to al-Qaida who had established a sanctuary there with weapons largely plundered in Libya during its 2011 civil war.

The French forced the jihadists to disperse, but did not crush them. The militants spread out across the region, and now proliferate all the way east to Egypt and south to Nigeria.

There's no hard evidence to suggest al-Qaida's involved in the CAR bloodletting, but the religion-based violence is a situation the jihadists could exploit.

The limited number of French and AU troops currently deployed in the Central African Republic may well prove to be too small to effectively control the whole of the vast country.

Some 400 French troops are pushing in from Cameroon, the CAR's western neighbor, giving the intervention force control of key highways linking the capital to the Cameroonian border and an area that includes the important cities of Bossangoa and Bouca, where the killing's been widespread.

These are centers of Seleka activity so more troops may be needed. France, not wishing to stuck with sole responsibility for pacifying the CAR, has been pushing for increasing AU force strength to 6,000.

But in the medium term, Hollande, facing mounting economic woes at home, could find himself embroiled in a risky military adventure in central Africa as he seeks to boost France's economic links with its former African empire.