The first time Azaan made the jump across the wall, he broke his arm.

Braving the 20ft (6m) drop into a wide trench below is, for many Afghans, the only way to cross into Turkey from Iran – and yet hundreds risk it each day.

“I was in severe pain,” the former Afghan army officer told the BBC.

“Several others had broken limbs. The smuggler left us here and told us to run in the direction of the lights of Van city. Many of us were fading out of hunger. I fainted.”

The wall – which stretches for nearly 300km (185 miles) – was built to prevent illegal crossings, and is patrolled constantly by Turkish border forces.

Jumping off it is among the first of a series of extraordinary risks Afghan migrants take as they cross continents, countries and seas to reach the UK and other countries in Europe.

Over the past year, fleeing their country has become more perilous than ever before for Afghans, because Pakistan, Iran and Turkey have intensified their crackdown on illegal migration from Afghanistan along their borders, and have also carried out mass deportations.

Azaan couldn’t continue. He was in pain, and had barely eaten in days. The migrants were given just one boiled egg every morning and a cup of rice in the evening by smugglers who’d charged them nearly $4,000 (£3,150) for the journey to Europe.

“I had two friends – we had made a promise to not leave each other,” he says. His friends tied scarves around him, hoisted him up the wall, back into Iran. Iranian police deported him to Afghanistan.

It was Azaan’s second failed attempt. The first time he returned from the Afghanistan-Iran border because he’d taken his wife and young children along, and he realised they wouldn’t be able to endure the journey.

Azaan didn’t give up. Roughly a year later, once his arm had healed, he made a third attempt.

“I had sold my house earlier. This time I sold my wife’s jewellery,” he says.