Brussels - The Taliban's stunning victory in Afghanistan and the prospect of new flows of un-vetted migrants into Europe have seized the attention of the EU's new counter-terrorism coordinator.

Senior official Ilkka Salmi is at pains to stress that the migrants and refugees leaving Afghanistan and Syria are fleeing crisis and conflict.

But European authorities cannot rule out the possibility that extremists are hiding among them, or that radicals unconnected to the migrants may be inspired by the Taliban victory.

"We have to keep in mind there is a possibility -- even if marginal, and it will be a marginal one -- but there is a possibility that there will be clandestine methods used by terrorists or people who are affiliated to terrorist organisations, that might try to enter the EU," Salmi told AFP.

"Again, I just want to underline the fact that it is mainly of course a humanitarian issue for many people coming to the EU, but at the same time we as the security authorities have to be also prepared for any other sorts of activity."

EU member states have been concerned about a possible new flow of migrants since August, when the hard-line Taliban movement seized the Afghan capital Kabul and overthrew the western-backed government.

After chaotic scenes at the airport, when desperate Afghans scrambled for evacuation flights, the feared exodus has yet to materialise -- but Afghanistan is now gripped by its worst drought in 22 years.

Belarus strongman Alexander Lukashenko, meanwhile, has exploited the EU's struggle to draw up a common asylum policy by luring Middle Eastern migrants and encouraging them to cross into Poland.

- Red flags -

And even if the number of migrants arriving in the EU has not soared, there are thousands gathered near the bloc's borders in the western Balkans, in north Africa and in Turkey.

Salmi notes in particular that the United States evacuated many Afghans from danger in Kabul -- but only as far as the western Balkans for processing.

If any of these are not allowed to fly on to the United States, Brussels will want to know why.

"If these people aren't admitted to the US what will be their future and why are they not admitted?" the former Finnish intelligence chief asked, in an interview with AFP.

"So it is also very important for the EU to understand why they might have been red-flagged," he said, adding that in recent weeks he has been visiting the western Balkans to study the issue.

In an action plan endorsed by EU interior ministers in October, Brussels asked that the US government share with member states or Europol the personal and biometric data of people in transit in the Western Balkans who are refused visas to enter the United States, as well as the reasons for the refusal.

The Taliban's victory in Afghanistan may also serve as a spur to similar jihadist groups threatening European interests and security.

And the retreat of NATO forces has made it much harder for western military intelligence to track events within the country.

- IS 'ideology remains' -

In general terms, beyond Afghanistan, Salmi -- who took on his counter-terror role in October -- sees the threat of terrorism as "relatively high".

"We have to keep in mind that even after the caliphate in Iraq, Syria, even if that was defeated, the Daesh ideology still remains and there will be an impact on the European security so we have to stay vigilant in that respect," he said, referring to the rout of the Islamic State extremist group.

While Islamist extremism is seen as the main threat by EU countries, far-right terrorism is also a high risk for countries like Germany, Salmi warned.

Heading a small team of ten people, the officer is responsible for advising and initiating EU legislation and policies.

Other priority issues for the coordinator include European jihadist fighters and their families held in camps in north-eastern Syria, run by US-backed Kurdish militias.

The US is pushing for the detainees to be repatriated and face justice or reintegration in their European homelands, but EU member states are reluctant to take responsibility for their citizens.

By Anne-Laure Mondesert