16 alleged jihadis have been arrested in Germany
The raids were carried out at 3am GMT (4am local time) in the western state of Hesse and targeted 16 alleged would-be jihadis.
Businesses, homes and mosques were targeted in the raids in Frankfurt, Darmstadt and Wiesbaden.
The main suspect of the sting operation is a 36-year-old Tunisian man who has been arrested during a raid in Frankfurt.
The unnamed man has been under investigation since August 2015 and is alleged to recruit and smuggle people for the Islamic death cult.
The accused are between the ages of 16 and 46.
An anti-terror officer in Germany
The pre-dawn raid saw 16 ISIS suspects arrested in Germany
Investigators believe the accused were plotting a terror attack but had not yet picked a location.
Hesse police are expected to hold a press conference at 9am GMT (10am local time).
They said the entire operation required the help of more than 1,100 police officers, investigators and officials.
'MERKEL MUST GO': Brussels protest against German Chancellor
Thu, January 12, 2017
Angry campaigners held placards with slogans reading 'Merkel not welcomed' and 'Merkel must go' following a spate of terror attacks against Germany.
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Protest on the sidelines of Angela Merkel's official visit in Brussels
It comes after Berlin police announced they had arrested three people in a mosque on Tuesday who are accused of plotting to travel to a foreign “war zone” – likely Syria or Iraq – to carry out an attack.
The mosque where the three men were apprehended is where Berlin Christmas market attacker Anis Amri is thought to have worshipped.