Nine people were reportedly arrested in a police operation in Greece's second-largest city Thessaloniki. The group -- reportedly consisting of eight Greeks and one Pakistani -- is accused of holding seven Moroccan migrants hostage in a house.

The suspects allegedly used physical violence against the migrants, recorded their actions on video and demanded extortion money from the Moroccans' families.

That's according to a variety of Greek media outlets, including Ekathimerini, which reported that the alleged perpetrators kept the victims in the house for two days and demanded 2,000 euros per person in ransom.

"The ordeal ended when one victim's family contacted authorities," Ekathimerini reported, which led to the suspects' arrest and the hostages' rescue. The alleged gang members now reportedly face criminal charges including kidnapping, extortion, human trafficking and organized crime.

According to Ellada24, the Moroccans arrived in Greece by crossing the Evros River from Turkey with the help of an unknown smuggler. They are believed to have walked to a nearby pick-up point, from where "gang members" took them by car to Thessaloniki, located around 300 kilometers west of the Greek-Turkish border.

None of the media outlets, which also included Greek City Times, stated exactly when the arrests took place; they also didn't cite a concrete source, only a "police investigation". InfoMigrants wasn't able to find a press release or similar to verify the information.

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Series of arrests

People suspected of smuggling and trafficking migrants are frequently arrested both inside and outside the EU.

Last November, for example, four suspected smugglers were arrested by Greek authorities and charged with facilitating illegal entry into the country and being part of a gang, among other things.

Migrant smuggling is a highly profitable and highly organized business. Some smuggling networks transport thousands of migrants to Europe. The arrests in Thessaloniki, moreover, highlights the dangers migrants face while trying to reach European countries with the help of smugglers.

Also in November, the bodies of four migrants were recovered off the island of Rhodes and a further 25 people were found alive on land, after an alleged migrant smuggler reportedly forced his passengers overboard after a boat journey from Turkey. The migrants told authorities they had been "threatened, intimidated, and beaten" by the alleged smuggler.

According to the UN Office on Drugs and Crime (UNODC), migrant smuggling is the "facilitation, for financial or other material gain, of irregular entry into a country where the migrant is not a national or resident."

The main difference between migrant smuggling and human trafficking, according to UNODC, is "financial or material benefit" vs. the actual exploitation of the victim and their person.