The U.N. refugee agency on Friday urged Serbia and Hungary to find a solution for the migrants camping in dire conditions at their border, hoping to enter the European Union despite border closures.

The UNHCR representative in Serbia, Hans Schodder, visited the small tent city that has formed at the Serbian side of the border next to the razor-wire fence that Hungary put up last year to keep the migrants away. Schodder said 300 migrants were at the camp, including families with small children and people with disabilities. He said some have been waiting for weeks without toilets or running water while relying on aid agencies for drinking water and food.

"This situation is not good at all," he said. "We hope, and we support, that the two governments will find a solution to put in place a process whereby the refugees and migrants don't have to wait in these conditions."

Hungarian authorities have been letting about 20 people a day into the country, mostly families with small children. Serbian government minister Aleksandar Vulin said authorities will try to persuade the migrants to move to nearby transit centers from where they could apply for entry into EU-member Hungary.

"This is the state border zone, it is not possible to camp here," Vulin said, adding authorities will not use force to make the migrants leave.

Migrants have been pushing to enter the EU despite the closure of the Balkan migration corridor in March and an EU-Turkey deal aimed at curbing the flow after over 1 million people came last year. Thousands have been stuck in the region for months, many seeking help from the smugglers to cross borders illegally.

The U.N. refugee agency also expressed concern Friday that migrants and refugees in Greece have been moved to several sites with "substandard conditions" after being evacuated from a makeshift camp near Greece's border town of Idomeni. UNHCR says they were taken to "derelict warehouses and factories" with "insufficient" food, water, toilets, showers or electricity — and said it was concerned that some families were being separated during the transfer.

At the Serbian-Hungarian border, Schodder said the situation there differed from Idomeni because the border is open for small groups of people. He warned that unless a "legal pathway" for entry into Hungary is established, the refugees likely will refuse to move — and aid workers are warning numbers of migrants could increase as the weather improves.

Ahmad Seeyar Wahaj, a 17-year old from Afghanistan, has been waiting for over 20 days to go to Hungary. He said he has seen other refugees come and go across the border, while he and his six family members were left waiting.

"Now we have lost our hope," said Wahaj, who wanted to reach Switzerland. "I want to go to high school ... I want to study law to be a lawyer."