BELGRADE, Serbia — They have come a long way, spent most of their money on smugglers and camped out in the open for weeks.

For Afghan migrants stranded in the Balkans there is no turning back, even as the most likely prospect many of them face in the European Union could be deportation back to their country.

Thousands of young Afghan men in Serbia and elsewhere in the region are determined to reach wealthy EU nations, despite closed borders and an agreement between their government and the EU that will more easily send home Afghan citizens who have been rejected for asylum.

Aid groups have sharply criticized “The Joint Way Forward” declaration, which was agreed upon only days ahead of an international donors’ conference Wednesday for Afghanistan that pledged $15.2 billion for the beleaguered country.

Imogen Sudbery, head of the Brussels office of the International Rescue Committee, says the plan “is worrying on several levels.”

“Deals made behind closed doors, thrashed out with no civil society engagement and without apparent consideration for people’s safety, nor the realities on the ground, set an alarming precedent for the EU,” Sudbery said. “The notion that vulnerable women and children can be sent back to a place of war is preposterous.”

The document outlines measures to return Afghan citizens, including charter flights, the issuing of travel documents and the possible construction of a separate terminal at Kabul Airport.

The EU declaration said the plan aims “to establish a rapid, effective and manageable process for a smooth, dignified and orderly return of Afghan nationals” who don’t receive asylum in the 28-nation bloc.

Afghanistan has been mired in conflict for decades. Clashes have revived recently between government forces and the Taliban around the northern city of Kunduz with civilians increasingly fleeing. Sudbery said 11,000 civilians were killed in Afghanistan last year and 1.2 million people remain internally displaced.

“Afghanistan cannot be considered a ‘safe country,'” Sudbery insisted.

Serbia is not part of the EU, making the situation for Afghans stuck here even more complicated. It has asked to be included in the EU-Afghanistan return arrangements.

Some migrants in Belgrade, the Serbian capital, said they are not safe in Afghanistan and have no way to finish schools, find jobs or earn money. The young men — who stand little chance of being granted asylum in EU countries — pleaded with EU nations to let them in so they can have a hope of a better future.

“Life in Afghanistan is too hard for us, we can’t live there,” said 15-year-old Sulaiman Zazai. “That is why we go to live in Germany, for a good life, for our future.”

Saifullah Zamiri, 18, added that “we struggle a lot in these bad conditions and with closed borders.”

“We can’t go back,” Zamiri insisted. “Our government can’t control a bad situation, so why do you want us to go back to our country?”

Germany and other EU nations have sought to limit the influx of refugees and migrants after taking in more than one million people last year. The German government says the joint declaration with Afghanistan will provide a “clear and reliable basis” for both voluntary returns and deportations.

IRC’s Sudbery blasted as “most damning” the clause that envisages that unaccompanied minors could be returned if “adequate reception and care-taking arrangements” are put in place in Afghanistan.

“It is unclear how the EU will measure or verify this,” she said.

Rados Djurovic, from Serbia’s Asylum Protection Center, said asylum-seekers from Afghanistan must not be automatically rejected but reviewed individually, considering that parts of the country are still dangerous.

“Each application should be taken most seriously,” he said.

Afghans account for about one half of more than 6,000 migrants who have piled up in Serbia after EU neighbor Hungary introduced strict limits on asylum-seekers and reinforced the border with a razor-wire fence and heavy patrols.

On Tuesday, several hundred men set off on a protest march toward Hungary, demanding that authorities there open the border. Tired and cold, the marchers gave up the next morning after walking 40 kilometers (24 miles) and spending the night out in the open.

On Friday, Serbian authorities discovered two Afghan boys, aged 12 and 16, hiding in a truck heading toward EU member Croatia.

In Belgrade, a park close to the railway and bus stations where migrants from Afghanistan spend their days and nights is now dubbed “Afghan park.”

On a sunny day last week, some migrants were sleeping on the benches wrapped in blankets at the park. A man was helping his friend shave without a mirror on the park’s water pipes. A woman was washing clothes and hanging them on a rope spread between two poles.

At lunch time, hundreds lined up for a warm meal of beans and beets distributed by a Belgrade aid group. Hunched over, the migrants ate their food on the ground or on the limited benches. Aid coordinator Gordan Paunovic says his Info Park center now delivers more than 2,000 meals a day in what he described as a “dramatic” increase in recent months.

Many migrants said they have already spent 5,000 to 6,000 euros ($5,600 to $6,700) to get to Serbia from Afghanistan with the help of smugglers after many European borders closed down in March. They usually travel through Iran, Turkey and Bulgaria before reaching Serbia.

Afghan young men are often sent to Europe to earn money to support their families back home, they said. Such is the case with Zazai.

“If they send us back, that will break our hearts,” he said.