ATHENS, Greece (AP) — Authorities in Greece have arrested three members of a charity helping migrants on the eastern island of Lesbos for allegedly belonging to a criminal organization that directly facilitated migrant smugglers for financial profit.

Police said Wednesday that a total of 30 Greek and foreign nationals, all members of the Greek non-governmental organization, are suspected of involvement.

The three people — a Syrian, a German and a Greek national — arrested on Lesbos and in Athens on Aug. 21 and on Tuesday are accused of belonging to a criminal organization, money laundering, espionage, forgery and breaches of immigration laws.

Police said they allegedly facilitated the illegal entry of migrants to Greece for profit, to raise donations or subsidies for the NGO's activities, had advance notification of smuggling boats' routes and numbers of passengers, and illegally monitored Greek and European coast guard radio traffic.

A Greek lawyer representing two of the suspects — German-based Syrian refugee Sara Mardini and German national Sean Binder — said his clients were doing volunteer work on Lesbos for the Emergency Response Centre International organization, and denied the charges.

"There is no evidence whatsoever that they have committed even one of the offences they are accused of," Haris Petsikas told The Associated Press on Wednesday. "On many of the dates when they are supposed to have committed offences they were not even (in Greece)."

Mardini and her sister Ysra — both competitive swimmers — arrived in Greece in 2015, swimming for their lives after jumping off an inflatable boat that began taking on water. Ysra was a member of the refugee team at the Rio Olympics.

Lesbos is a major entry point for migrants and refugees illegally crossing over from nearby Turkey. Since Europe's migration crisis hit a peak in 2015, it has become a base for many charities helping migrants. More than 10,000 migrants are currently stranded on the island.

Petsikas said there was no proof that ERCI members were in contact with migrant traffickers.

The arrests followed an investigation launched in February, after two members of the NGO were stopped on Lesbos in a jeep with fake Greek military number plates under its own license plates.