Athens: Hundreds of migrants stranded at a makeshift Greek camp protested near the border with Macedonia on Sunday, demanding that the border be opened as they clung to hopes of making it into Europe despite new EU moves to send some refugees back. Around 50,000 migrants and refugees remain trapped in Greece after a domino of border closures by countries along the Balkan route has prevented them from continuing their journey into wealthier European countries. Many live in squalid conditions in tents near the town of Idomeni at the border with Macedonia. Some 400 protesters gathered at the camp on Sunday, waving white napkins and holding signs that read "open the border". A man with a megaphone led them singing folk songs in Arabic. Greek police formed a line to prevent the protesters from moving to the fence that separates the camp from Macedonia. "We're here today, and everyday, because we won't give up. We protest here everyday for the sake of women and children," said a Syrian woman, Hana. "We are humans and we have rights, this is why we are here today and we will keep protesting until the borders open." Greece has said it was a priority that migrants left the Idomeni camp and has boosted efforts to convince them to move to nearby shelters. It was also speeding up the creation of reception centres for up to 30,000 migrants to help cope with a sharp rise in numbers because of border closures. The European Union and Turkey have agreed to stop the migrant flow to Europe in return for political and financial concessions for Ankara, in a bid to seal off the main route by which people have poured across the Aegean islands. Under the EU-Turkey deal, hundreds of new arrivals have been detained since March 20, while refugees or migrants whose applications fail will be sent back to Turkey. About one million people arrived in Greece last year, fleeing conflict in Syria, Iraq and other countries in the Middle East and Africa. Meanwhile, in Zurich, Austria's interior minister has called for tougher measures to protect the European Union's borders from returning militant fighters, Austrian newspaper Oesterreich reported on Sunday. "We know that more than 5,000 people travelled to Syria and Iraq to be trained or even to fight," Interior Minister Johanna Mikl-Leitner told the paper. "So it's more pressing than ever that EU citizens be systematically controlled at the outside borders in the future," she said. Austria - the last stop before Germany, the top destination for migrants - has come under fire for its tough immigration stance. Vienna has said it will introduce tougher checks at its border with Italy and has urged the EU to send soldiers to Greece to police the bloc's frontiers. In a separate interview with Austrian newspaper Oberoesterreichische Nachrichten on Sunday, Austrian Chancellor Werner Faymann said German Chancellor Angela Merkel's policy of upholding Germany as an asylum magnet was unfair on Austria. He urged the German chancellor to speak out against migrants trying to break through various borders to access the country. "Merkel's policy can cause damage to Austria. We don't want to be Germany's buffer zone," Faymann said. On Saturday, members of Merkel's conservatives said Europe urgently needed to improve the way its security agencies share information, stoking a debate on how to tighten security while safeguarding data protection. "Faster communication is important so that tips about possible attacks can be quickly assessed and terrorist acts can be prevented if possible before they take place or cleared up in a more focused way," Germany's EU Commissioner Guenther Oettinger told the daily Bild.