PARIS (Reuters) - France will not negotiate with gunmen claiming to be from Nigerian Islamist group Boko Haram who have taken a French family of seven hostage, Defence Minister Jean-Yves Le Drian said on Tuesday.
The three adults and four children were seized in north Cameroon near the Nigerian border last week. In a video posted online, the gunmen threatened to kill them unless authorities in Nigeria and Cameroon freed Islamist militants held there.
The kidnapping brought to 15 the number of French citizens held in central and west Africa and highlighted the danger to French nationals and interests in the region since Paris sent troops to Mali last month to help oust Islamist rebels.
Le Drian said the fighting in Mali was not close to an end and troops were facing stiff resistance from the "strongest and most organized" rebels, underscoring the risk of French and African forces becoming entangled in a messy guerrilla war.
The French defence minister deplored the fact children were among the hostages seized in Cameroon and ruled out talks with their captors, saying: "We do not play this bidding game because that's terrorism."
"We do not negotiate on that kind of basis, with these kind of groups," he told RTL radio. "We will use all (other) possible means to ensure these and other hostages are freed."
The abduction was the first case of foreigners being seized in the mostly Muslim north of Cameroon, a former French colony. But the region - with typically porous borders - is considered within the operational sphere of Boko Haram and fellow Nigerian Islamist militants Ansaru.
Boko Haram, one of a number of al-Qaeda linked groups in the region, has killed hundreds of people in an attempt to establish an Islamist state in Nigeria.
"The principle of terrorism is the same whether you are in Somalia with the Al Shabaab, in Mali with Ansar Dine or in Nigeria with Boko Haram or Ansaru," Le Drian said. "It's the same system, the same methods, which threaten us here in France and so we must eradicate them."
The video posted online on Monday showed the hostages, including the four boys, surrounded by three gunmen wearing turbans and camouflage gear.
"The president of France has launched a war on Islam and we are fighting it everywhere," said one of the apparent kidnappers, identifying himself as a member of Boko Haram.
In Mali, French and Chadian troops are encountering strong resistance from die-hard al Qaeda-linked Islamists in the mountainous north, Le Drian said.
Chadian troops launched an offensive at the weekend against fighters holed up in the Adrar des Ifoghas mountains near the Algerian border but suffered the heaviest losses since the international offensive began last month.
Chad's armed forces said some 23 of its soldiers and about 90 rebels were killed in the fighting. French fighter jets and helicopters were forced to support the Chadian offensive.
"The most fundamentalist elements are there," Le Drian said. "The strongest and most organized forces. We expected resistance and we've had some extremely violent battles."
Paris intervened in its former West African colony last month to stop a southward offensive by Islamist fighters who seized control of the north last April.
After quickly driving the rebels out of major urban areas, France and its African allies have focused on the remote northeast desert and mountains - an area the size of France that includes networks of caves, passes and porous borders.
Asked about the timing for pulling out the 4,000 French troops, Le Drian said it was hard to give a precise timetable. He said it would take a "certain amount of time" to secure the north-east completely.
"The intervention was very fast and enabled the entire territory to be liberated in 45 days. What's left is the hardest part," he said. "It's pretty much meter by meter, in a vast territory, but that's where these groups are hiding out."
"If things evolve normally, we could begin leaving before the end of March," Le Drian said. "As soon as this operation is over then we will begin the withdrawal."
Rebels have staged bombings and raids mainly targeting Mali's poorly trained and equipped army in northern cities.
The minister said Paris had already spent "a little more than 100 million euros ($132 million)" on the operation.
($1 = 0.7567 euros)
Reporting by Nick Vinocur; Writing by Catherine Bremer and John Irish; Editing by Pravin Char