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Muhammed Muheisen, Associated Press
In this Monday, Jan. 30, 2017 photo, unaccompanied minor, Irfan, 17, a migrant from Pakistan's tribal area of Bajaur, stands in an abandoned warehouse where he and other migrants took refuge in Belgrade, Serbia.

BELGRADE, Serbia — In an abandoned warehouse in the Serbian capital of Belgrade, Rasool, a 12-year-old from Jalalabad, Afghanistan, has spent the last six months sleeping on the ground, warming himself by fires, showering with cold water and eating meals distributed by aid groups.

"This place is so cold and dirty, the smoke from burning fires hurts my eyes and lungs," he said. "I close my eyes every night and open them in the morning wishing to hear from my elder friends that the border is open and leave to be with my cousins in London."

He's among dozens of minors, mostly from Afghanistan and Pakistan, living in the warehouse with hundreds of other, older migrants. Their parents sent them alone to Europe in search of better futures, but they have been stuck in Serbia, unable to cross the heavily guarded borders of neighboring EU nations Croatia and Hungary.

Governments along the so-called Balkan migration route last year closed down their borders as part of efforts to stem a huge influx of migrants. Previously, people arrived by boat or land from Turkey, then could walk or take trains or buses and cross borders freely from eastern Europe to destinations in western Europe.

Since borders closed last March, thousands of migrants have been stranded in Serbia, waiting for them to reopen or trying to scrape together enough money to pay smugglers to take them.

Rasool says his mother and father supported his efforts to leave Afghanistan because the Taliban made it unsafe and he wanted to study and have a peaceful life.

"I miss my parents so much," he said.

Liaqat, a 12-year-old from Khogyani, Afghanistan, said he left nine months ago, traveling to Pakistan and then on through Iran, Turkey and Bulgaria before arriving in Serbia. He and three new friends do everything together, and he's learned how to cook.

"If we don't cook ourselves we will be hungry," he said, stirring rice, potatoes and onions over the fire. "I am hoping to reach Belgium if they open the border, a beautiful country where I can be safe, study and become a doctor to help people."

Caesar, a 16-year old from Pakistan's tribal area of Bajaur, offered the daily Muslim afternoon prayer at the spot where he sleeps in the warehouse, then talked about how the minors on their own help take care of each other, with the older ones guiding the younger ones.

"It is difficult to live under these circumstances but still safer than hometowns here we live in fear for our lives," he said.

Muhammed Muheisen is The Associated Press' chief photographer for the Middle East, Pakistan and Afghanistan and a two-time Pulitzer Prize winner. Follow him on Twitter: https://twitter.com/Muheisen81 and Instagram: https://www.instagram.com/mmuheisen