Britain and the United States have warned that the Boko Haram extremist group was preparing to kidnap foreigners in remote northeast Nigeria.
The Foreign Office in London said Friday it had received reports the militants were “actively planning” to seize foreign workers in the Bama local government area of Borno state.
Both said in travel advice that the affected area was “along the Banki-Kumshe axis”, which is near the border with Cameroon.
The US embassy in Abuja said in a message to its nationals that the report was “credible”.
Boko Haram has kidnapped thousands of women and children, including more than 200 schoolgirls from the Borno town of Chibok in 2014, which brought the conflict to world attention.
At least 20,000 people have been killed since 2009. But abductions of foreigners have been rare.
There was a spate of kidnappings of foreign workers in the wider north from 2011 to 2013, claimed by a Boko Haram splinter group, Ansaru, which was more ideologically aligned to Al-Qaeda.
The leader of Ansaru, Khalid al-Barnawi, has been charged with the abduction and murder of foreigners, most of them engineers or construction workers.
International aid workers now account for the majority of foreign nationals in northeast Nigeria. Most are based in the Borno state capital, Maiduguri.
Hundreds of thousands of people in the Lake Chad region require urgent food aid as a result of the conflict, which has made more than 2.6 million people homeless and ravaged farmland.
Nine Chadian soldiers were killed in a Boko Haram attack on an army post in the Lake Chad region on Friday, local and security sources told AFP.
Some 40 Boko Haram jihadists were also killed as the army responded to the attack on the Kaiga post, sources said on condition of anonymity. A military official confirmed the attack without giving a toll.