Jihadists have dynamited bridges and mounted deadly attacks against supply convoys, blockading Burkina Faso's northern town of Djibo and leaving its people destitute.
"The situation is catastrophic in Djibo," said Idrissa Badini, a spokesman for a group of civil society organisations in the wider Soum province.
"Hunger is at such a level that it is starting to kill children and the elderly."
Last month alone, 15 people died of hunger in the town, he said. But there were "probably more victims", as other cases had likely gone unreported.
According to the United Nations, dozens of places in Burkina Faso face conditions similar to those in Djibo.
Nearly a million people are living in besieged areas in the north and east of the country.
Burkina Faso has been struggling with a jihadist insurgency since 2015.
Over the last few years, Djibo has become a hub for the region's internally displaced people, forced to flee violence involving groups linked to Al-Qaeda and the so-called Islamic State organisation.
The town's population has tripled to an estimated 300,000.
But the blockade is now pushing some of those displaced to flee a second time, southwards to the capital Ouagadougou.
"Deprived of water, food, medicine and phone signal, many are leaving Djibo on foot, at night, in the hope of reaching areas they can still reach," an aid worker told AFP on condition of anonymity.
Eating leaves to survive
On the road between Djibo and the town of Bourzanga, residents described seeing the wreckage of vehicles hit by landmines.
Several supply convoys have recently been attacked on the road.
The World Food Programme says around 3.5 million people in Burkina Faso will need emergency food aid in the coming months. By Issouf SANOGO (AFP)
In September, 35 people died when their truck was blown up by a mine. There were children among the dead.
Another attack on a convoy killed 11 soldiers.
The convoys are a lifeline -- with farmers unable to tend to their fields amid the fighting, food production is almost non-existent in many parts of Burkina Faso.
"There's nothing to eat, nothing to sell. Whether you're poor or rich, you can't buy anything," said Souleymane Dicko, a Djibo resident who had escaped to the capital Ouagadougou.
"The worst thing is we're in the dry season -- the leaves and herbs we used to pull up and boil aren't even available anymore."
Disgruntled army officers have carried out two coups in Burkina Faso this year in a show of anger at failures to roll back the insurgency.
Earlier this month, Captain Ibrahim Traore, who seized power in a coup in September, went to Djibo on his first official visit.
"Go and see the children who have skin on their bones, the old people who are dying of hunger, the women who can no longer breastfeed because they have nothing left in their breasts," Traore said.
"Let's not pretend. There are people who eat leaves to survive."
He described a "worrying situation", saying "the territory is almost lost".
'Verge of a humanitarian disaster'
In Arbinda, a town to the east of Djibo, tens of thousands of people from surrounding areas have gathered fleeing attacks.
Burkina Faso's leader Captain Ibrahim Traore, who seized power in September, chose to go to Djibo on his first official visit. By OLYMPIA DE MAISMONT (AFP)
"The regular land convoys that used to supply the population with food and subsistence products have stopped," said Badini.
"For the past two months, nothing has reached Arbinda. The population, which has used up its reserves, is on the verge of a humanitarian disaster."
In some cases, some supplies have been able to get through to areas in need despite the attacks.
At the end of last month, the army airlifted 70 tonnes of grain to Djibo, and trucks ferried in more than 300 tonnes of food to the town at the start of this month, the army general staff says.
Seven mines were defused on the way.
"We have been able to supply some villages but not others yet," Traore said.
The World Food Programme says around 3.5 million people in Burkina Faso will need emergency food aid in the coming months.