About 400 Nigerian soldiers have fled into neighbouring Cameroon to escape intense fighting with Boko Haram in the border town of Banki, which the insurgents captured on Tuesday, Voice of America (VOA) reported late yesterday. The station attributed the report to Cameroon’s state radio but gave no further details.

The alleged incident came on the heels of last week’s unprecedented development in which nearly 500 Nigerian troops crossed over into Cameroon following fierce fighting with Boko Haram. Nigeria’s Defence Headquarters (DHQ) had described it as a tactical maneuver. The affected Nigerian soldiers have since returned home and to their duty posts. DHQ has yet to respond to the latest incident.

The VOA report quoted U.S. Assistant Secretary of State for African Affairs Linda Thomas-Greenfield as saying that the U.S. will soon launch a major border security programme to help Nigeria and neighboring countries fight Boko Haram.

The report said that Thomas-Greenfield, while speaking to officials in the Nigerian capital Abuja yesterday, made the disclosure against the background f Boko Haram’s alleged seizure of the city of Bama and other locations in the north-eastern state of Borno.

She was quoted as saying that the U.S. is “very troubled by the apparent capture of Bama” and the prospects for an attack on Borno state capital, Maiduguri.

“The frequency and scope of Boko Haram’s terror attacks have grown more acute and constitute a serious threat” to Nigeria’s overall security, Thomas-Greenfield said.

Boko Haram, which means “Western education is a sin,” has killed thousands of people since launching an insurgency against the Nigerian government in 2009. The group also kidnapped more than 200 girls from a school in the town of Chibok in April.

Nigeria’s government declared a state of emergency in three states last year and deployed thousands of troops to fight the group. However, analysts have said the terrorists appear to have better weapons and equipment than government security forces.

•Photo shows Boko Haram leader Abubakar Shekau.