T he civil war in Darfur robbed Hager Shomo Ahmed of almost any hope. Raiders had stolen his family’s cattle and a dozen years of bloodshed had left his parents destitute.

Then, around the end of 2016, Saudi Arabia offered a lifeline: the kingdom would pay as much as £7,869 if Hager joined its forces fighting 1,200 miles away in Yemen.

Hager, 14 at the time, could not find Yemen on a map, and his mother was appalled. He had survived one horrific civil war – how could his parents toss him into another? But the family overruled her.

“Families know that the only way their lives will change is if their sons join the war and bring them back money,” Hager said in an interview last week in the capital, Khartoum, a few days after his 16th birthday.

The United Nations has called the war in Yemen the world’s worst humanitarian crisis. An intermittent blockade by the Saudis and their partners in the United Arab Emirates has pushed as many as 12 million people to the brink of starvation, killing some 85,000 children, according to aid groups.

Abdel-Hamid, a 14-year-old former child soldier, at a camp for displaced persons where he took shelter, in Marib, Yemen (Photos AP/ Nariman El-Mofty) (AP/ Nariman El-Mofty)

Led by Crown Prince Mohammad bin Salman, the Saudis say they are battling to rescue Yemen from a hostile faction backed by Iran.

But to do it, the Saudis have used their vast oil wealth to outsource the war, mainly by hiring what Sudanese soldiers say are tens of thousands of desperate survivors of the conflict in Darfur to fight, many of them children.

At any time for nearly four years, as many as 14,000 Sudanese militiamen have been fighting in Yemen in tandem with the local militia aligned with the Saudis, according to several Sudanese fighters who have returned and Sudanese policymakers. Hundreds, at least, have died there.

Almost all the Sudanese fighters appear to come from the battle-scarred and impoverished region of Darfur, where some 300,000 people were killed and 1.2 million displaced during a dozen years of conflict over diminishing arable land and other scarce resources.

Most belong to paramilitary Rapid Support Forces, a tribal militia previously known as the Janjaweed.

They were blamed for the systematic rape of women and girls, indiscriminate killing and other war crimes during Darfur’s conflict, and veterans involved in those horrors are now leading their deployment to Yemen – albeit in a more formal and structured campaign.

Some families are so eager for the money they bribe militia officers to let their sons fight. Many are aged between 14 and 17.

In interviews, five fighters who have returned from Yemen and another about to depart said that children made up at least 20 per cent of their units. Two said children made up more than 40 per cent.

To keep a safe distance from the battle lines, their Saudi or Emirati overseers commanded the Sudanese fighters almost exclusively by remote control, directing them to attack or retreat through radio headsets and GPS systems provided to the Sudanese officers in charge of each unit, the fighters all said.

“The Saudis told us what to do through the telephones and devices,” said Mohamed Suleiman al-Fadil, a 28-year-old member of the Bani Hussein tribe who returned from Yemen at the end of last year. “They never fought with us.”

Sadek, another 14 year-old former child soldier at a camp in Marib (AP/ Nariman El-Mofty)

“The Saudis would give us a phone call and then pull back,” agreed Ahmed, 25, a member of the Awlad Zeid tribe who fought near Hodeidah this year and who did not want his full name published for fear of government retaliation.

“They treat the Sudanese like their firewood.”

A few thousand Emiratis are based around the port of Aden. But the rest of the coalition assembled by the Saudis and Emiratis is united mainly by dependence on financial aid.

The Pakistani military, despite a parliamentary vote blocking its participation, has quietly dispatched 1,000 soldiers to bolster Saudi forces inside the kingdom. Jordan has deployed jets and military advisers.

Both governments rely heavily on aid from the Gulf monarchies. A report by a UN panel suggested Eritrea may have sent about 400 troops as well.

But in Sudan, which has played a far larger role, the Saudi money appears to flow directly to the fighters – or mercenaries, as critics call them. It benefits the economy only indirectly.

“People are desperate. They are fighting in Yemen because they know that in Sudan they don’t have a future,” said Hafiz Ismail Mohamed, a former banker, economic consultant and critic of the government.

“We are exporting soldiers to fight like they are a commodity we are exchanging for foreign currency.”

A spokesperson for the Saudi-led military coalition said it was fighting to restore the internationally recognised government of Yemen and that coalition forces upheld all international humanitarian and human rights laws, including “abstaining from child recruitment”.

Ambassador Babikir Elsiddig Elamin, a spokesperson for Sudan’s foreign ministry, declined to comment on troop levels, casualties or paychecks in Yemen. He said Sudan was fighting “in the interest of regional peace and stability”.

“Other than that,” he added, “we don’t have any national interest in Yemen.”

Nawaf, a 15-year-old former child soldier, in Marib (AP/ Nariman El-Mofty)

President Omar al-Bashir of Sudan has gained valuable allies, easing his international isolation after years as a virtual pariah.

The US has designated Mr Bashir’s government a state sponsor of terrorism for more than two decades. The International Criminal Court has issued warrants for his arrest, charging him with directing the Darfur war crimes.

Until recently, the Saudis and Emirates kept their distance, suspicious of Mr Bashir’s roots in political Islam and relations with Iran and Qatar, both Saudi rivals.

The war in Yemen, however, has enabled Mr Bashir to win at least diplomatic support from its Gulf leaders, and he has thanked the Saudis and Emiratis for pressing Washington to upgrade relations.

The Saudi payments to the soldiers have become increasingly significant to Sudan, where inflation has hit 70 per cent and even in the capital residents line up for bread, fuel and bank withdrawals. At least nine people have been killed this month by security forces.

The five fighters who had returned from Yemen and two brothers of fighters who died there all gave similar accounts. Sudanese jets departed Khartoum or Nyala in Darfur, carrying 2,000 to 3,000 soldiers at a time to Saudi Arabia.

They were delivered to camps inside the kingdom, where some said they saw as many as 8,000 Sudanese gathered.

The Saudis gave them uniforms and weapons, which the Sudanese fighters believed were US-made. Then Saudi officers provided two to four weeks of training, mainly in assembling and cleaning their guns.

Finally, they were divided into units of 500 to 750 fighters, they said. Then they travelled over land to Yemen, to battles in the Midi Desert, the Khalid bin Walid camp in Taiz, or around Aden and Hodeidah.

All said they fought only for money. They were paid in Saudi riyals, the equivalent of about £377 a month for a 14-year-old novice to about £417 a month for an experienced Janjaweed officer.

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They received an additional £146 to £224 for any month they saw combat – every month for some.

Their payments were deposited directly into the Faisal Islamic Bank of Sudan, partly owned by Saudis. At the end of a six-month rotation, each fighter also received a one-time payment of at least 700,000 Sudanese pounds – roughly £7,869 at the current official exchange rate.

By comparison, a Sudanese doctor working overtime at multiple jobs might earn the equivalent of £393 a month, said Mr Mohamed, the economic consultant.

Abdul Raheem, 32, a member of the Rezeigat tribe whose full name was withheld to prevent reprisals, said last year his family paid a local militia leader a bribe worth £1,070 so an older brother could go to Yemen as an officer.

The brother, Abdul Rahman, died in combat in February. “Life is like that,” Abdul Raheem said.