Europe faces a second wave of terror attacks when ISIS supporters serving short sentences are released from jail, the boss of Interpol has warned.

Jürgen Stock said ISIS 2.0 could plague the continent when an 'early generation' of supporters is released.

Because ISIS has no territory left in the Middle East, supporters will either head to Africa or stay in Europe to commit terror attacks, he said.

Europe faces a second wave of terror attacks when ISIS supporters serving short sentences are released from jail, the boss of Interpol has warned. Pictured: An ISIS soldier in Syria in 2014

Stock told the Press Association in Paris: 'We could soon be facing a second wave of other Islamic State linked or radicalised individuals that you might call Isis 2.0.

'A lot of these are suspected terrorists or those who are linked to terrorist groups as supporters who are facing maybe two to five years in jail.

'Because they were not convicted of a concrete terrorist attack but only support for terrorist activities, their sentences are perhaps not so heavy.

'In many parts of the world, in Europe but also Asia, this generation of early supporters will be released in the next couple of years, and they may again be part of a terrorist group or those supporting terrorist activities.

Stock, a German criminologist, said that Interpol has a database of about 45,000 suspected foreign jihadists, many of which are very hard to track down.

'The so-called returnees are still a concern for many member countries,' he said.

'Many of those who left, for instance from Europe or Asia, have not yet returned. Some of them have been killed on the battlefield but some of them are missing.'

Maren Ueland (right), 28, from Norway, and Louisa Vesterager Jespersen (left), 24, from Denmark, were found dead in Morocco's High Atlas mountains on Monday

He warned: 'The security agencies are concerned about when they are coming back because most of them are battle hardened, they are trained and they are internationally connected.'

Stock became the boss of the International Criminal Police Organization which has 194 members in 2014.

Stock's comments came after ISIS terrorists in Morocco filmed themselves decapitating a Scandinavian woman.

Maren Ueland, 28, from Norway, and Louisa Vesterager Jespersen, 24, from Denmark, were found dead near the village of Imlil in Morocco's High Atlas mountains on Monday.

A video showing the murder of one of the women has been recognised as genuine, Danish intelligence service said today, adding that the killings can be connected to ISIS.

Men in the gruesome clip can be heard shouting 'it's Allah's will' while there are claims that the words 'this is for Syria' were used, in an apparent reference to Western bombing missions in the war-torn country.