Police in Macedonia have fired tear gas and stun grenades after hundreds of frustrated Iraqi and Syrian refugees tried to force their way through a razor-wire barrier across the border into the southeastern European country from Greece.
Tensions flared on Monday, with thousands of desperate refugees stuck for days on the Greek side of the border, overflowing from a packed refugee camp at Idomeni.
"The situation is very hectic; people just want a safe passage," Vicky Markolefa, of the Doctors Without Borders (MSF) aid organisation, told Al Jazeera from Idomeni.
"We denounce violence against innocent refugees."
MSF treated many refugees for respiratory problems after they had tear gas fired on them, she said. Women and children were among those caught up in the crowds.
Markolefa said people were forming 400-metre lines just for food.
READ MORE: Syrian refugee's new life in Spain
"We are overwhelmed. NGOs [non-governmental organisations] are doing their best to respond, but we are calling for European governments to act now."
MSF said on Twitter that it had treated one patient suffering from tear-gas injuries who was just six weeks old.
Al Jazeera's Hoda Abdel-Hamid, reporting from Idomeni, said a rumour that the border crossing with Macedonia was opening brought hundreds to the razor-wire barrier.
"There was a state of panic and hope that finally those gates towards Western Europe would open. It's an emotional rollercoaster for these refugees and migrants who are here," she said.
| Athens square becomes temporary camp as refugees are stranded
About 50 refugees were allowed into Macedonia on Monday.
"The refugees are saying, 'What we've seen here is going to divide opinion in Europe'," our correspondent said.
"It's a completely different atmosphere at the moment from last year and they are aware of it. People are saying, 'This is not going to help us. They will see this and we will not be welcome'."
Refugees in limbo
Nearly 8,000 refugees are in limbo at the Idomeni border camp which has a capacity of 2,000, according to Greek officials.
Many are spread out into the surrounding fields as they wait for Macedonian authorities to let them continue their trek through the Balkans.
Only a tiny trickle of people from specific countries have been allowed to cross every day.
Later in the day, Macedonia sent special police reinforcements by helicopter to its border with Greece.
More than one million refugees and migrants have passed through the camp in the previous 12 months, travelling from Turkey to Germany and other Western European countries, where they hoped to secure asylum.
Known as the Jungle, the Calais camp was used by refugees who wanted to migrate to Britain [Pascal Rossignol/Reuters]
Elsewhere on the continent, French authorities on Monday began dismantling part of a refugee camp known as the "Jungle" near Calais, after an expulsion order issued by the local administration was upheld last week by a judge.
Workers in bright construction vests and helmets took down tarps and sheets of material that had been cobbled together to create shelters at the camp, which was home to those seeking a future in nearby Britain.
Scores of riot police stood guard, keeping journalists and volunteers out as helmeted workers tackled the shelters one by one.
Fabienne Buccio, a police prefect who had ordered the camp to be evacuated and dismantled earlier this month, showed up as the operation began.
Her office decried "intimidation" tactics by some activists who, she said, were manipulating migrants into refusing to accept government offers of shelter.
"Really three houses out of four - I mean three huts out of four, or three tents out of four - were already totally abandoned with a lot of garbage inside," she said.
Migrants, she said, "had the time necessary to gather their belongings. The rest was good enough to throw away."
After first sending welcoming messages, European authorities are now struggling to handle the situation.
Hungary has fenced off its borders, refusing to accept any migrants, and other Eastern European countries say they will not take in anyone under an EU refugee-sharing deal.
In recent weeks Austria - at the north end of the Balkan corridor - has severely restricted the inflow of refugees, causing a domino effect through the Balkans.
Many of those countries are now refusing to let Afghan refugees in, although UN authorities say no one has explained to them who made this decision or why.
Diplomatic tensions are rising, too, with criticism mounting against Austria. Greece has threatened to block decisions at a forthcoming EU-Turkey summit unless the bloc forces members to shoulder more of the refugee burden.
For her part, German Chancellor Angela Merkel issued on Sunday another robust defence of her quest for a European solution to the crisis.
She is resisting calls at home and elsewhere in Europe for limits on refugees such as those imposed by Austria.
"We can't do this in such a way that we simply abandon Greece," she said on ARD television.
"This is exactly what I fear: When one country defines its limit, another must suffer. That is not my Europe."
At next Monday's summit, EU leaders "will discuss how we can restore the [passport-free] Schengen system step by step with Greece", Merkel said.
However, Reinhold Mitterlehner, Austria's deputy chancellor, said on Monday that the refugee restrictions "are necessary [and] we're going to maintain them".
| Refugees stranded at Macedonia-Greece border
Source: Al Jazeera and agencies