A Red Cross employee has been killed and another injured in a gun attack by suspected Islamist militants in Mali, the aid organisation says.
Armed men opened fired on an aid vehicle as it travelled from Gao to Niamey in neighbouring Niger to pick up medical supplies.
The International Committee of the Red Cross (ICRC) said in a statement that it was "profoundly dismayed" by the killing.
Islamist militant group Mujao told AFP that it had carried out the attack.
The nationality of the ICRC worker who was killed has not yet been released.
"He was driving to collect much-needed medical equipment for a Gao hospital," said Yasmine Praz Dessimoz, head of operations for North and West Africa.
"His death is not only a tragedy for his family and for the ICRC, it will affect the life and well-being of tens of thousands of people," she added.
The injured worker was a member of the national Mali Red Cross and is in a stable condition in hospital.
The vehicle the pair were travelling in was clearly marked with the Red Cross emblem and was later burned.
"The ICRC is concerned about the rise in violence against humanitarian workers, which is preventing them from coming to the aid of individuals and communities in dire need," Ms Praz Dessimoz said.
A spokesman for Mujao, Abou Walid Sahraoui, was quoted by AFP as saying: "We have achieved what we wanted with this attack."
Mujao, which stands for Movement for Oneness and Jihad in West Africa, was formed in 2011 to spread jihad across West Africa and it believed to be a well-disciplined group.
Mali's desert north suffers frequent militant attacks despite a French-led operation to drive out Islamist fighters in 2013.
Earlier this month, a rocket attack on a UN base in Kidal killed a Chadian peacekeeper and two children.