Cameroonian troops this month crossed into Nigeria in pursuit of rebels without seeking authorization from Nigeria, causing a falling-out between the governments behind the scenes, sources familiar with the matter told Reuters.
At least one incursion was confirmed by a Nigerian government official, two Nigerian military officers and two foreign diplomats, all of whom spoke on condition of anonymity.
Nigerian security forces were deployed to the border to stop any further crossings, said a military source.
The Cameroonian and Nigerian governments said in separate statements there were no incursions. Relations between the two countries are good, Cameroon said.
Cameroonian military officials and pro-government media accuse Nigeria of sheltering Anglophone insurgents. For the past year they have been based in the dense equatorial forests that straddle the border between the two countries, fighting for an independent state they call Ambazonia.
At least 7,000 people have fled as refugees from Anglophone Cameroon to Nigeria following a crackdown ordered this year by President Paul Biya to quell the insurgency, which represents the gravest challenge yet to his 35-year rule.
French is the official language for most of Cameroon but two regions speak English and these border Nigeria, which is also Anglophone.
“Cameroonian troops were in Nigeria,” said a foreign diplomat. “Zero warning, zero authorization.”
The troops crossed into Nigeria at least twice this month, the diplomat and a Nigerian military official told Reuters.
The incidents have caused anger on both sides and could sour diplomatic relations further as Cameroon increases pressure on its Anglophone regions, according to the diplomat and a Nigerian government official.