The official referred to Paris bombings saying that two of the perpetrators originally came from Syria and entered France through Greece and the Balkans after registering themselves as refugees, German newspaper Deutsche Wirtschafts Nachrichten (DWN) reported.
"I think it is possible that the Islamic State [Daesh] deliberately urged two bombers enter here through Greece and undergo the process of registration," Maassen said.
About 1.1 million people from Middle Eastern and North African countries immigrated to Germany in 2015, raising criticism and security concerns among the local population and German politicians.
"[…] the refugee issue determines not only the media coverage and the social and political debate on the federal and local level. It is also increasingly gaining importance in the agitation and activities of extremist actors," Maassen said.
According to him, the new situation has led to the rise of right-wing extremism and increased the possibility of an Islamist or a right-wing attack in the country. Moreover, there are concerns that about 260 of 800 young people who travelled to Syria to wage jihad and then came back to Germany could commit terrorist attacks on the German soil.
"Every day we receive between two — four warnings about possible attacks in Germany," Maasen said. He also added that refugees often become subject to radical indoctrination by extremist groups.
"There are currently about 300 indications about direct contacts of Islamists to asylum seekers. These occur mainly at or near the refugee centers," the official said.