The almost instant takeover of most of Afghanistan by the Taliban in a week, leaving the capital Kabul surrounded and set to fall, has led to worries more refugees will flee the terrorists wrath and try to get to Greece through Turkey.

They've been coming for almost six years already, making up much of the nearly 100,000 refugees and migrants who came to Greece in detention, seeking asylum after the European Union closed its borders to them.

With Syrians fleeing a long-running civil war there, Afghans trying to get away from war make up the majority of refugees and migrants in Greece, many waiting two years or more for sanctuary applications to be processed.

The EU's border agency FRONTEX – which, along with Greece's New Democracy government has been accused of pushing back people trying to reach Greek islands from Turkey – is using high-tech surveillance equipment to detect boats used by human smugglers in the Aegean, said the Reuters news agency.

A balloon system equipped with cameras is being tested at Alexandroupolis airport near the Greek-Turkish land border in northeastern Greece, and on the island of Limnos, to give an early line of sight of dinghies and other craft that could be filled with refugees and migrants.

They use Turkey as a jumping off point and pay smugglers to get them to Greece, which had welcomed them in the early days of arrivals in 2015 but now doesn't want any more and has been trying to deter them from coming.

The surveillance was planned before the Taliban surged through Afghanistan which is being abandoned by the United States and NATO after 20 years of fruitlessly trying to beat back the terrorists.

“We are observing and following the developments specifically in Afghanistan and Tunisia which might have an effect on migratory flows towards the European Union,” FRONTEX spokesperson Piotr Switalski told the news agency.

A mix of cameras and thermovision sensors with links to ship transponders and satellite communications gives officials a real-time view of a 60 kilometers (40 miles) circle of sea, covering 40,000 square kilometers (15,000 square miles).

“Border surveillance in the maritime area should be greatly improved because of this innovative system,” he said.

FRONTEX has deployed in Greece a force of 400 people and several dozen vehicles, including some equipped with thermovision technology, as well as eight patrol vessels.

Greece has denied pushing back anyone despite constant accusations from human rights groups, activists and Turkey, which hasn't been sanctioned or punished for violating the terms of an essentially-suspended 2016 swap deal with the EU by letting traffickers keep sending refugees and migrants to Greece.

Several EU countries have stopped forced returns of Afghans refused asylum while the fighting intensifies but Greek Migration Minister Notis Mitarachi said this week the EU could not handle another major migration crisis.

Switalski said arrivals in Greece spiked in July, with some 1,000 detections but the numbers had dropped dramatically after the swap deal that was supposed to see Turkey taking back those deemed not eligible for asylum. The numbers slowed more because of the COVID-19 pandemic.

Switalski said the “tricky” geopolitical situation in the region around the EU has heightened fears of more waves of Afghan refugees who at one point were so many in Greece they occupied parks and even some city squares in Athens.