$2,800 for a bride!

Fahima has wept many times since her husband sold their two young daughters into marriage to survive the drought gripping western Afghanistan.

Oblivious to the deal, six-year-old Faristeh and 18-month-old Shokriya sit by her side in a mud-brick and tarpaulin shelter for displaced people.

"My husband said if we don't give away our daughters, we will all die because we don't have anything to eat," Fahima said of the choice now facing thousands of Afghan families.

"I feel bad giving away my daughters for money."

The oldest commanded a bride price of $3,350 and the toddler $2,800 -- to be paid in instalments over several years until the time comes to join their new families, their future husbands still minors themselves.

Child marriage has been practised in Afghanistan for centuries, but war and climate change-related poverty have driven many families to resort to striking deals earlier and earlier in girls' lives.

Boys' parents can drive a harder bargain and secure younger girls, spacing out the repayments.

The World Food Program warned Monday that more than half the population of Afghanistan, around 22.8 million people, will face acute food insecurity from November.

In Qala-i-Naw, capital of the western province of Badghis -- one of the regions worst affected by the drought -- there is shame and grief.

Village and displaced people's camp leaders say the numbers of young girls getting betrothed started to rise during a 2018 famine and surged this year when the rains failed once more.

Among farmers driven from their homes, AFP journalists quickly found more than a dozen families who felt forced to sell their daughters into marriage.

Fahima's 25-year-old neighbour in the camp, Sabehreh, ran up a bill at a grocer's shop to feed her family. The business owner warned that they would be jailed if they could not repay him.

To cover the debt, the family agreed that their three-year-old daughter, Zakereh, would be betrothed to the grocer's four-year-old son, Zabiuallah.

Another neighbour, Gul Bibi, confirmed that many families in the camp had resorted to child marriage.

Her own daughter Asho, aged eight or nine, is betrothed to a 23-year-old man to whose family Gul Bibi was indebted. The young man is away in nearby Iran, and she dreads the day of his return.

"We know it's not right, but we don't have the choice," commented Hayatullah, a passer-by who overheard the mother's sad tale.

In another Qala-i-Naw camp, Mohammad Assan wiped back his tears as he showed AFP photos of his girls, Siana, nine, and Edi Gul, six, now living far away with their young grooms.

"We've never seen them since," he said. "We didn't want to do that, but we had to feed our other children."

"My daughters are surely better off over there, with food to eat," he reasoned, trying to console himself as he showed AFP the crusts of bread his neighbours spared for him.

The Taliban's interim governor for Badghis province, Maulvi Abdul Sattar, told AFP: "These child marriages are due to economic problems, not to any rule imposed by the Islamic emirate, or the Sharia."