5 suspects were arrested early Friday in a counter-terrorism operation conducted by Istanbul police, according to security sources.

Axar.az reports citing Anadolu.

The suspects were held for links to the ISIS terror group, said the sources who asked not to be named due to restrictions on talking to media.

The detentions took place during raids in four districts -- Silivri, Bagcilar, Maltepe and Gungoren.

The raids resulted in the capture of twelve foreign nationals who were suspected to be attempting to travel to conflict zones, the sources added.

A large body of digital data and documents were seized during the operation, according to the sources.