ISTANBUL: As refugees try to use a land route from Turkey as an alternate way into the European Union, Ankara has begun enforcing long-dormant rules on Syrians’ travel, in part over concerns about how the flow is affecting the country’s image, according to a government document obtained by The Associated Press and interviews with officials and migrants.

So far the moves appear ad hoc and aimed only at preventing refugees from reaching the Turkish frontier city of Edirne, where hundreds are staging a sit-in near the Greek border. But one academic said it was a sign of a more-determined effort by Turkey to get a handle on the country’s massive refugee population.

“In the case of Syrians, this is the first time they are trying to be strict on movement,” said Ahmet Icduygu, who directs the Migration Research Center at Istanbul’s Koc University. “They’re clamping down.”

The one-page Interior Ministry document, dated Aug. 29, says officials consider that “Syrians who are trying to go to third countries through our country illegally are posing a threat to public order and public security and are negatively affecting our country’s image internationally.”

It orders checks on Syrians’ documents at the entrance and exit to each province and asks law enforcement to tell transport companies that Syrians are not allowed to leave the provinces where they have registered without permission. The document only refers to Syrians, who constitute the overwhelming majority of Turkey’s roughly 2 million refugees. The effect of the order, whose authenticity was confirmed by two government officials, was that hundreds of Syrians who tried to reach Edirne to join their fellows last week found themselves stuck for days just outside a sprawling bus terminal in Esenler on the European side of Istanbul.

Hundreds of people, most of them Syrian, camped for days in and around a nearby mosque, many sleeping rough behind a cordon of police in riot gear.

Most were mystified by the refusal of bus companies to sell them tickets.

“I don’t know why they say no, really,” Muthana Al-Abdullah, a 22-year-old engineering student from Aleppo, told the AP at Esenler.

Three bus company managers at the station confirmed that they had been instructed to refuse tickets to Syrians. On Sunday — when the crowds were leaving — one of the managers said rules had been relaxed again.

Ankara has been extraordinarily generous to people from Syria in the years since civil war broke out there. The number of refugees Turkey hosts far outstrips all neighboring European countries put together and has turned the country into the world’s No. 1 host of refugees overall. But even though the Turks have spent some $7.6 billion feeding and housing the influx, many struggle to make ends meet. “There is no future for my my children here at all,” said Mohammed Ali Al-Baya, a 40-year-old cell phone salesman from Aleppo who was among those stuck at the bus station.

He and his compatriots say they don’t want to risk the dangerous boat trip across the Aegean Sea taken by so many others and had organized with the help of a Facebook group to travel to Edirne and try to walk to Greece en masse and on foot. That border rush appears to have been a step too far for Turkish officials, who continue to block the refugees who reached Edirne from approaching the border. For Al-Baya and others stuck at the station, it was it the first time they had ever been prevented from traveling within Turkey.

One senior government official said the Interior Ministry document was a reminder of pre-existing rules that bar Syrians from leaving the province they have registered in. He said the aim was to prevent “unauthorized mobilizations” and that Syrians with travel passes could still circulate freely. He spoke on condition of anonymity because he was not authorized to be named.