BERLIN — German police representatives warn of a serious security risk linked to refugees who have entered the country without being properly registered. According to the Police Trade Union and the German Union of Police Forces, only a fraction of incoming immigrants have had their fingerprints registered over the past few months, leaving an estimated tens of thousands of asylum seekers in the country who haven't undergone proper procedures.

In a recent letter addressed to German Chancellor Angela Merkel, the Police Trade Union's Jörg Radek wrote that the federal police are "not capable of exercising their duty of danger prevention and law enforcement at the German-Austrian borders the way they are legally bound to."

The letter says that in "hundreds of thousands of cases," the German Border Patrol has absolutely "no idea who enters the country, under what name, and for what reason," a problem that officers say endangers state security.

ISIS captured thousands of passports

Die Welt has reported that ISIS had seized thousands of genuine passports in Syria, Iraq and Libya, which prompted Fabrice Leggeri, chief of the EU border management agency Frontex, to warn: "The waves of people entering Europe unchecked obviously represent a security risk." At least two of the terrorists in the Nov. 13 Paris attack had been registered as refugees in Greece.

"The security risk results from a deficit of controls at borders," says German Union of Police Forces chief Rainer Wendt. Law enforcement officials say that criminals exploit the chaos, making use of the waves of refugees to enter Germany unnoticed.

Says Police Trade Union's Radek: "Over the last couple of months, we have controlled not more than 10% of the incoming refugees."

After the Paris attacks in Paris, investigators quickly discovered that two of the terrorists had come to Europe by passing themselves off as refugees. Two of the passports found on the terrorists' bodies had been registered on the Greek island Leros on Oct. 3.

There are indications that other dangerous Islamists entered the country the same day — probably planning a future attack, according to the German National Security Authority. It is also at the origin of two refugees arrested in Salzburg, Austria, it emerged this week.

"Can't be ruled out"

"Considering the large number of immigrants, it can't be ruled out that among them could be criminals, members of militant groups or terrorist organizations, or individuals with extremist dispositions who were making use of the flow of migration to come to Germany," a source at the German Interior Ministry says.

The ministry warned in November of a surge in black market passports. Practically any Syrian document can be purchased. "As a result of the Syrian state of war, blank documents and seals, and software and hardware for their illegal replication, might have fallen into the hands of criminal organizations," the agency says.

André Schulz, chief of a federal detective union, confirms it's possible that terrorists are among the refugees. But, he adds, that risk has always been there with the open-border Schengen Area. What he considers more problematic is the fact that jihadists are equipped with ten thousands of real passports and machines to produce more.

So many undocumented

For experts of the Federal Police and Bavarian Border Patrol, it's not particularly complicated to recognize fake documents. Schulz says it's more problematic if falsified papers are being printed with real printers in the country of origin. "Those documents might have been captured by terrorists," he adds, "or the person is being infiltrated voluntarily by the government." An even bigger problem is the fact that most of the immigrants are carrying no documents with them at all, making identification difficult or impossible.

According to police estimates, only 25% to 30% of the immigrants coming to Germany through Austria carry a passport or another form of identity. "Passport inspections can't rule out all of the risk," Radek says. Nevertheless, he says that controls have become more effective thanks to new technical equipment and more personnel. "But if the number of immigrants continues to rise, we still won't be able to keep up," he adds.

There is an extra cruel irony that terrorists are infiltrating the ranks of desperate refugees. "Many of the immigrants are trying to escape ISIS," he says. "And now the same terror group is discrediting them in the new place where they've arrived."