Seven French tourists, including four children, have been kidnapped by gunmen in Cameroon, near the border with Nigeria, French President Francois Hollande has said.
Francois Hollande says they belong to the same family and were seized by a “known terrorist group based in Nigeria”.
The president added that the seven were probably taken to northern Nigeria.
He indicated that the Nigerian Islamist militant group Boko Haram may have been responsible.
“I see the hand of Boko Haram in that part of Cameroon, and that is worrying enough for us to mobilize,” Francois Hollande said.
He said everything possible was being done to rescue the family and warned other French nationals in northern Cameroon to avoid “exposing themselves”.
The family had been returning from a visit to Waza National Park when they were attacked by men on motorcycles, Cameroonian officials said.
The incidents come amid a French-led intervention against Islamist militants in Mali.
Seven French tourists, including four children, have been kidnapped by gunmen in Cameroon, near the border with Nigeria
At least eight French nationals were already being held by Islamist groups in Africa.
Boko Haram has staged many attacks across northern Nigeria in recent years, targeting churches, government buildings and the security forces.
Another Islamist group- Ansaru – is also active in the region.
On Sunday, Ansaru claimed the abduction of seven foreign workers in Nigeria.
Italian, British, Greek and Lebanese workers are thought to be among those held after an attack on a construction project in Bauchi state.
Ansaru also says it is holding a French national, Francis Colump, who was seized in the northern state of Katsina.
At least six foreign workers have been seized and a security guard shot dead by gunmen who attacked a construction company site in Bauchi, northern Nigeria, officials say.
One of the workers seized was Italian, one was Greek and two others Lebanese.
No-one has admitted the abductions but the Islamist militant group, Boko Haram, has staged a series of attacks in northern Nigeria.
A security guard was killed as the attackers targeted the workers’ camp at Jama’are in Bauchi state.
Correspondents say it is the biggest kidnapping in northern Nigeria in recent times.
The kidnapping of foreigners and wealthy Nigerians is common in the oil-rich Niger Delta region, in the south of the country, and has become a lucrative trade for criminals.
Oil workers and other foreign nationals are often targeted because companies pay high ransom money to secure their employees’ release, correspondents say.
Lebanese foreign minister Adnan Mansour said two of those held were from Lebanon.
An Italian and a Greek national were also abducted from the site run by Lebanese-owned firm Setraco, the foreign ministries in Rome and Athens confirmed.
Another of those seized was a Filipino, said a union leader at Setraco.
At least six foreign workers have been seized and a security guard shot dead by gunmen who attacked a construction company site in Bauchi, northern Nigeria
The Italian ambassador in Abuja said: “Italy’s absolute priority is the safety of its compatriot,” Ansa news agency reported.
The raid was preceded by an attack on the local police station, when two vehicles were blown up, in the town of Jama’are, some 125 miles north of the state capital, Bauchi.
The attackers then moved on to a camp belonging to Setraco, killing a guard and seizing the workers. Setraco is currently expanding a major road in the area.
The state capital has itself been attacked several times by Boko Haram, which wants to impose Sharia (Islamic law) across Nigeria.
Earlier this month, nine polio vaccinators were shot dead at two health centres in northern Nigeria.
Some Nigerian Muslim leaders have previously opposed polio vaccinations, claiming they could cause infertility.
Boko Haram has emerged as one of the most prolific militant groups in West Africa, carrying out a large number of low-level attacks but also some more sophisticated attacks.
Twelve people, including polio vaccinators, have been killed in two shootings at health centres in northern Nigeria.
In the first attack in Kano four polio vaccinators were shot dead by gunmen who drove up on a motor tricycle.
Thirty minutes later gunmen opened fire on women waiting with their children in Hotoro, outside Kano city.
In 2003, northern Nigeria’s Muslim leaders opposed polio vaccinations, claiming they could cause infertility.
Kano banned motorbikes from carrying passengers after a recent attack on the prominent Muslim leader, the emir of Kano.
Residents said that those injured in the shooting at the health centre there had been taken to hospital.
Twelve people, including polio vaccinators, have been killed in two shootings at health centres in northern Nigeria
It is not clear if health workers were among the casualties in Hotoro, where gunmen also approached using a motor tricycle.
Analysts believe the attack last month on the emir of Kano may have been the work of the militant Islamist group Boko Haram.
The group – whose name translates as “Western education is forbidden” – says it is fighting to overthrow the government and impose Sharia.
It has been blamed for the deaths of some 1,400 people in central and northern Nigeria since 2010.
Nigeria is one of only three countries where polio is still endemic.