German intelligence chief BfV Hans-Georg Maassen called for the implementation of systematic prescribed procedures in the handling of thousands of refugees in Germany on a daily basis, saying extremists can take advantage of the occasional chaotic situation.
The deadly attacks in Paris on Friday, killing at least 129 people, prompted a debate in Germany on the open arms of Angela Merkel's chancellor towards refugees and how to gain a better insight into who are people entering the country.
Europe has been hit by the worst migration crisis since World War II, and Germany assumes the bulk of the cargo and is expected to enter the 800.000 refugees and migrants this year.
"It is possible that there are terrorists among the refugees, but we find it less likely," Maassen said in an interview with several local newspapers on Sunday.
"For security services, it is important to have systematic prescribed procedures regarding entry into Germany and the implementation of asylum procedures," he said.
While German police are currently conducting passport checks at border crossings and border areas, it is believed that thousands of refugees come to the country without any verification.
Maassen said the refugee route from Syria and Iraq to Turkey, Greece and the north across the Balkan countries was extremely dangerous. "It would be risky and unethical that people who have a combat mission come from Turkey to the Greek islands in the boat of death."
He expressed concern that radical Islamists who were already in Germany could try to recruit young migrants.
"We note that Islamists approach refugees at reception centers. We already know about more than a hundred cases, "he said.
In his words, radical Islamists look at the refugee crisis as an opportunity to recruit people for their goals.
Interior Minister Thomas de Maiziere and Economy Minister Sigmar Gabriel warned of premature links between the Paris bombings and refugee talks.