Europe's open borders are being exploited by Islamic State and pose "a huge risk of terrorism", an expert has warned.

Richard Walton, former Met Police head of counter-terrorism, said Berlin lorry attacker Anis Amri's journey across Europe highlighted the vulnerability of the Schengen zone, which allows passport-free travel between most EU states.

Amri was killed in a shootout with police in the Italian city of Milan on Friday morning - four days after the rampage that left 12 dead.

Police said the 24-year-old, who pledged allegiance to IS, fled Germany after the attack and made it to Chambery in France, where he travelled by train to Turin, northern Italy, before stopping in Milan.

Image: Anis Amri came to Europe from Tunisia

Mr Walton said the journey was evidence of "porous borders across mainland Europe".


"They (IS) have a clear strategy and have set out to carry out attacks across mainland Europe," he told The Daily Telegraph.

"Europe's weakness is our weakness. We need European countries to get their act together.

He added: "Sooner or later, they are going to get across the Channel."

Image: Amri travelled by train across Europe after the attack

Britain is not a part of Schengen. The EU's 31-year-old accord covers continental EU states - except for newer members Romania, Bulgaria and Croatia - as well as Switzerland.

Amri arrived at Milan's Central Station at 1am on Friday and made his way to the suburb of Sesto San Giovanni, where he was shot dead after pulling a gun on police who stopped him for ID.

Chris Phillips, former head of the National Counter Terror Office, told Sky News the ease by which the Tunisian slipped out of Germany was "really worrying" and "a sign of the times".

He said: "We've seen this in the past with the Paris attackers making their way back to Brussels without any difficulty at all. It's a big problem."

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Tony Smith, former director general of the UK's border force, echoed the concerns.

He told Sky News: "He had no ID documents after the event, there was a full manhunt in place.

"Nonetheless he was able to cross two or three borders before he was eventually apprehended and even then really on the basis of more of a suspicious routine stop rather than an intelligence-led operation.

"So, it does beg the question, what is the Schengen group going to do about their borders?

"And in particular, how are they going to respond to critical incidents like this in the future?"

However, another expert, former Europol director Max-Peter Ratzel, said he did not see a "structural failure" in the Schengen agreement.

"Even by border controls there would not be any guarantee that he would have been stopped in between," he told Sky News.

"I would not say that this is a major failure of the Schengen area. There may be some slight failures or some slight errors, but it's not a structural failure of Schengen - I would deny that."

Image: Police officers cover the body of Amis Amri in Milan

Former UKIP leader Nigel Farage and the leader of France's National Front, Marine Le Pen, have demanded the EU scraps freedom of movement after the attack.

Mr Phillips said Germany, France and Belgium had "serious problems" when it comes to monitoring terrorists.

Talking about Germany, he said: "They want to be a very free, open, democratic society - of course we all do.

"But they've got a natural disinclination to have things like CCTV cameras and the arms of the state that actually do protect you in times of terrorism."

Mr Phillips added: "If you think back to the London attacks, we were able to follow the suspects right back to the start of their journey, right back to their car journey when they were in the petrol station filling up with petrol and we knew from that who these people were and what they were on their way to do."