The Yemeni officer was relieved that he had just a few metres left of Aden's airport to clear, when the ground suddenly buckled, lurched upwards and propelled him into the air.

Ali Salah, 55, said his team had already pulled out more than 580 mines and explosives from the terminal, once a battleground between Yemen’s recognised government and the Gulf coalition backing them on one side and the Shia Houthi rebel group on the other.

The de-mining team had one last corner to work on before the skeleton carcass of the building could finally be declared safe. But then Salah stepped on something.

When he came around, his right leg had vanished. One month later his son Kamel, 20, would suffer a similar fate, ending up in the same hospital. The 20-year-old driver was transporting a mine clearance team around the southern port city when his car clipped an anti-tank mine along the road.

Like a mirror image of his father, Kamal lost his left leg.

“We were both doing our jobs, but it cost us our legs,” Salah told The Independent as he tapped his prosthetic limb inside one of the few centres in Aden that is trying to fit amputees with artificial limbs.

Behind him, two wounded children waiting for treatment played together as best they could. One of them, Emad, 14, lost both legs during a mortar attack outside his home.

Salah was injured three years ago, but his colleagues are still digging up mines from areas around Aden.

“This is one of Yemen’s toughest problems now. It will take a lifetime to sort,” he added.

The threat of mines, improvised explosive devices (IEDs) and explosive remnants of war, known as ERWs, left behind in the fighting is the untold threat facing civilians in Yemen.

Saudi Arabia said this week that the Houthis had laid about a million landmines and IEDs across Yemen since the war broke out in 2015. On the other side of the country Yemeni government officials said they have uncovered half-a-million ERWs, mostly left by al-Qaeda.

There is no way of independently verifying these figures, as international monitoring teams lack access. There is also an issue surrounding the definition of a mine: mine clearance crews in Yemen will regularly call everything from an IED to a mortar shell a mine.

But officials within the United Nations Development Programme (UNDP), which is supporting local projects on the ground, said problems caused by the explosive ordinances littering Yemen could take “decades” to fix.

Yemen is in the grips of a devastating three-year conflict between the Iran-backed Houthis and the recognised Yemeni government, the latter supported by a coalition headed by Saudi Arabia and the United Arab Emirates. More than 10,000 people have been killed in the fighting which, according to the United Nations, has sparked the world’s largest humanitarian crisis in terms of numbers: some 22 million people, or three-quarters of the population, rely on aid to survive.

Further east in the country, coalition-backed Yemeni troops are also locked in a battle with al-Qaeda which, until recently, controlled a 700km stretch of territory along Yemen’s southern coast.

Much has been reported about the direct impact of the fighting but little about the devastating effects of these weapons left behind.

Yemen's battle to clear the country of landmines and explosives Show all 10 1 /10 Yemen's battle to clear the country of landmines and explosives Yemen's battle to clear the country of landmines and explosives Emad, 14, lost both his legs in a mortar attack near Aden, Yemen Bel Trew/The Independent Yemen's battle to clear the country of landmines and explosives Young trainees are schooled in how to identify mines and Improvised Explosive Devices in Mukalla, Yemen Bel Trew/The Independent Yemen's battle to clear the country of landmines and explosives Information leaflets warn civilians of the dangers of landmines in Yemen Bel Trew/The Independent Yemen's battle to clear the country of landmines and explosives A young boy looks out the window of a prosthetic limb and rehabilitation centre in Aden, Yemen Bel Trew/The Independent Yemen's battle to clear the country of landmines and explosives Land mines IEDS, and suicide belts found by the mine clearance teams are laid out during training sessions Bel Trew/The Independent Yemen's battle to clear the country of landmines and explosives This suicide belt packed with nails was made by al-Qaeda militants in south Yemen Bel Trew/The Independent Yemen's battle to clear the country of landmines and explosives The de-mining teams have compiled booklets educating local populations about looking out for mines and IEDS Bel Trew/The Independent Yemen's battle to clear the country of landmines and explosives Posters line the walls of a training centre alerting civilians to the dangers of mines Bel Trew/The Independent Yemen's battle to clear the country of landmines and explosives These anti-tank and anti-vehicle mines are among thousands pulled out of the ground by mine clearances crews every year Bel Trew/The Independent Yemen's battle to clear the country of landmines and explosives Mine clearance crews say Al-Qaeda militants make their own suicide vests as well as victim-activated explosive devices Bel Trew/The Independent

According to the UNDP, in the first six months of this year Yemen’s top de-mining agency, the Yemen Executive Mine Action Centre, cleared nearly 140,000 explosive remnants of war across 5 million square metres – a process that cost $2.4 million. Between 2016 and 2017 the UNDP said the action centre had cleared more than 510,000 ERWs across at least nine governorates.

"The mine action centre has been completely overwhelmed by the current situation. There is no way they have enough resources to deal with it,” said one UNDP official who asked not to be named.

“The current levels of contamination will take years to sort and there will be residual risks for a considerable time after that. We need to get survey teams on the ground – even if they can just release ground to say it’s safe,” he added.

Human Rights Watch (HRW) said in its latest report that since 2015, mines and explosive devices appeared to have killed and maimed “hundreds of civilians”. The rights group has repeatedly urged the Houthis and their allies to cease using the indiscriminate and banned weapons, and to observe the 1997 Mine Ban Treaty, which Yemen ratified in 1998.

HRW officials now warn that the knock-on effects of the mines will impact a far larger population.

"You have people who, two years on from the end of fighting in their area, cannot return home, because they’ve been told it’s mined. Their livelihoods are therefore destroyed,” Kristine Beckerle, HRW’s Yemen and UAE researcher, told The Independent.

“Humanitarian aid workers also can’t access areas where there are believed to be mines or IEDs, so it impedes humanitarian response,” she added.

Farmlands are often mined or laced with explosives as well, meaning people cannot make a living.

“There are secondary and tertiary effects that are quite devastating,” she said.

On the other side of the country, near the port city of Mukalla, which between April 2015 and April 2016 was a stronghold for al-Qaeda, a group of new trainees learn how to identify mines and IEDs in rudimentary, battered kit. Their dangerous but vital work is backed by a mix of funding from UNDP, the Red Cross and the UAE.

Access to proper kit is one of the main problems they face, according to the director of the training centre, whose name has been withheld for security reasons.

“When al-Qaeda left they took all the de-mining and bomb disposal equipment with them, which just made our job even harder,” the centre's head told The Independent.

“The militants and the Houthis have been making their own devices, like this victim-triggered one here,” he said, handling an array of home-made IEDs and suicide belts packed with nails and ball bearings designed to maim.

“They put them on the main highway, we found 50 on a beach. They put them in houses. Some are so sensitive even a chicken can trigger it,” he added.

The current levels of contamination will take years to sort... The mine action centre has been completely overwhelmed by the current situation UNDP official

Behind him, a dozen or so young men in military fatigues and flimsy-looking protective gear were completing a two-month training course before going into the field. Some crawled on their knees along a prepared assault course looking for the tell-tale signs of a buried explosive.

The trainees said that although they are scared of the mines, for them the toughest challenge was dodging car bombs and suicide attacks from the embattled militants. Right now, the teams are mostly focused on clearing areas north of Mukalla, where al-Qaeda has hunkered down in the hills.

“Around six of my friends have died from mines so far,” said Salah, 30, a father-of-two and new recruit, taking a break in the blistering heat of the summer sun.

“It’s scary work but for us the most dangerous things are the car bombs we face on the way to work.”

His trainer, Ahmed, 43, a veteran de-miner from Aden, has been in the business since he was just 16 years old. He said over the years more than 40 of his friends have been killed de-mining.

Despite decades of experience, he said the mine problem has never been so bad.

“Right now is the worst days for mines. It’s a thousand times worse now than it ever has been because in this part of Yemen we are dealing with militants who lay them randomly,” he told The Independent.

Just two weeks ago he nearly stepped on a mine near Wadi Masini, a two-hour drive north of Mukalla and a former al-Qaeda stronghold, which the militants lost to Yemeni forces in February this year. The team said it takes a whole day just to clear 25 square metres of land there, because it is so densely packed with explosives.

“Right now, is the worst days for mines. It’s a thousand times worse now than it ever has been Ahmed, de-mining trainer in Mukalla

Ahmed described the moment that saved his life: when out of the corner of his eye he spotted a tiny flicker of metal winking from among the short grasses. He knew it was an anti-tank mine when his metal detector chirruped and clicked over a gentle rise in the ground. One unwise move would have been his end.

“I was so close,” he added, grinning. “Every day we face death. But if we don’t do it, who will?”

Back in Aden, Abdullah al-Qaisi, the head of the city’s prostheses and psychotherapy centre, begged for funds to help his teams.

The parents of double amputee Emad, who dragged himself along the floor, said the teenager was hit by a mortar during the 2015 war but has had very little support. Mohamed, four, who is waiting for a new leg, was held by his father, Marwan, who said they were both injured by Houthi snipers in the same year. Behind them a young girl in her early 20s sat silently, holding the stump of her arm.

“We lack everything but mostly the raw materials to make the artificial limbs. We have no funding and we need to make on average between around 50 limbs per month,” al-Qaisi said.