Slabs of concrete have sprung up in recent days, snaking for just over one kilometer over the rolling hills of Hatay province, a finger of land which was part of Syria until the late 1930s.

Turkey has kept an open-border policy throughout Syria's three-year civil war and has vowed to maintain it, providing a lifeline to militant groups battling President Bashar al-Assad by allowing supplies in and refugees out. But the policy has had its costs.

Smuggling has also thrived, and a growing number of Syrians forced by the war to eke out a living where they can, swell the ranks of those trying to cross back and forth outside the official border posts.

That has compounded the challenge of securing the 900-km border for Turkey's authorities, already accused of doing too little to stop foreign terrorists from entering Syria and posing an even bigger risk to the wider region.

Car bombs in the Turkish town of Reyhanli killed dozens almost a year ago and there has been more violence since then.

The International Crisis Group estimates that more than 75 Turkish citizens have been killed in fighting that has spilled over the frontier.

"Turks are reminded of the security risks by deadly car bombs and armed incidents on their territory, especially as northern Syria remains an unpredictable no-man's land," the think-tank said in a report.

"The conflict was not of its making, but Ankara has in effect become a party," it said.

Turkey's handling of the Syrian war has imposed on the economy in border areas and fears about terrorist groups have also alarmed local people.

NJF/NJF