It is believed the group are Islamic State militants planning to make their way to Germany posing as refugees.
Anadolu said the eight claimed to be tourists visiting Istanbul but a hotel refuted claims they had reservations there.
The arrests come as Europe is on high alert following the terror attacks in Paris which have left 129 dead and hundreds injured.
The Syrian operative claimed more than 4,000 covert ISIS gunmen had made it into western nations, hidden among innocent refugees.
He said members of the blood-thirsty group were following the well-trodden route taken by refugees and migrants fleeing Syria, travelling across the border of Turkey then on to boats across to Greece and through Europe.
He said it was the beginning of a larger plot to carry out revenge attacks in the West in retaliation for the US-led coalition airstrikes.
He said extremists are taking advantage of developed nations' generosity towards refugees to infiltrate Europe, he said.
More than 1.5million refugees have fled into Turkey alone – desperate to escape the bloodshed in Syria.
From Turkish port cities like Izmir and Mersin, thousands of refugees venture across the Mediterranean aiming for Italy, he said.
He said: "They are going like refugees.
"It’s our dream that there should be a caliphate not only in Syria but in all the world."
Two Turkish refugee-smugglers backed up the claims made by the terrorist.
One admitted to helping more than ten trained ISIS rebels infiltrate Europe under the guise of asylum seekers.
He said: "I’m sending some fighters who want to go and visit their families.
"Others just go to Europe to be ready."