He also stated his office was aware of 7,900 radicals living in Germany

Hans-Georg Maasen said he believed they are planning 'combat missions'

ISIS jihadis determined to carry out attacks in European cities are entering the continent hidden among migrants, a German police chief says.

Hans-Georg Maasen, a federal police chief, claimed ISIS extremists hardened on the battlefields of Iraq and Syria are blending in with the migrants and are planning 'combat missions' in Europe.

In the wake of the Paris attacks it was revealed several of the gunmen and suicide bombers - who helped slaughter 130 people - had reached the city via Greece posing as asylum seekers.

German police believe ISIS extremists are entering Europe to carry out attacks by posing as migrants

According to the Austria Press Agency, Mr Maasen said his office was aware of almost 8,000 Islamic radicals in Germany.

He said all of these extremists advocate violence to advance their goals, with some trying to win over migrants, and his office receives one or two 'fairly concrete tips' of planned terrorist activity a week.

He went on to describe ISIS extremists as 'combat-hardened professionals' more dangerous than those from al-Qaeda.

His warnings comes just nine days after it emerged eight migrants have reached Europe using documents almost identical to those carried by one of the Paris suicide bombers.

The passport, found near the body of one of those who participated in the massacre of 130 people, identified him as Syrian.

It showed he claimed asylum on the Greek island of Leros last month with the fake Syrian passport in the name of 25-year-old Ahmad Almohammad.

But nine days ago Serbian police revealed they had arrested a man carrying a Syrian passport which was almost a carbon copy of the one found on the ISIS bomber’s corpse.

It had the same name, date of birth and place of birth. The only difference was the photograph.

Forgery fears: The passport found on a Paris body's bomber outside the Stade de France. Eight migrants have reached Europe using documents almost identical to these

French special forces clear people from the Bataclan theatre where 89 people were killed two weeks ago

Police tape and a covered body lie outside the Bataclan after terrorists opened fire on concertgoers

Serbian officials said as many as six other men this year had entered the EU with virtually identical passports.

The discovery has heightened fears that all the documents are fakes made by the same forger in the Middle East to dupe authorities into believing the holders are asylum seekers.

And worse, it has sparked concerns that the bogus papers could be in the possession of jihadists now lurking undetected in the EU’s passport-free Schengen travel zone.

The shocking ease with which the terrorists who murdered 130 innocent people in Paris were able to travel across Europe has sparked a renewed debate about the open borders policy.

The development raises fresh worries over the potential security threat posed by 670,000 asylum seekers who have arrived in Greece this year after fleeing war and poverty.

Meanwhile, today Czech President Milos Zeman stated Prime Minister Bohuslav Sobotka was endangering his country by not fully recognizing the danger asylum-seekers are posing.