This comes after an aid worker from the charity Médecins du Monde was killed after being shot by soldier at a military base in north-eastern Nigeria.

Another soldier was killed and a UN helicopter pilot was also injured in the incident.

Thursday’s shooting will have sent chills down the spines of the humanitarian and diplomatic community.

Tensions have been high since the US embassy evacuated all its non-essential staff from Abuja last month, citing a credible threat of attack. Many have been waiting to see whether an attack on a foreign institution would materialise.

Perhaps this explains why the military was quick to claim that the shooting in Damboa was the act of a rogue soldier, who had been “neutralised”.

But the incident will add to the feeling that insecurity is on the rise in Nigeria.

The UN’s Humanitarian Air Service carries aid workers to and from Maiduguri, the capital of Borno state, which is the epicentre of a decade-long Islamist insurgency. All helicopter travel to the field has been suspended indefinitely.