Turkish and German police on Wednesday announced major coordinated raids against a criminal trafficking network that used unseaworthy ships to send more than 1,700 refugees to Europe.

The operation was a major strike against international organised crime fuelling the record migrant wave to Europe, police chiefs from both countries told a press conference at Potsdam outside Berlin.

In 17 pre-dawn raids, more than 490 German police officers and commandos arrested five suspects across six German states, said federal police chief Dieter Romann.

Similar raids took place in Turkish cities including Istanbul, Ankara and Mersin, where 30 arrests were made, Turkish national police chief Mehmet Lekesiz told the joint press conference.

The human traffickers allegedly bought three old and decrepit cargo ships in Turkey, loaded each with hundreds of paying migrants and sent the vessels on autopilot toward the Italian coast.

Taking up to $6,000 (5,500 euros) from each of the more than 1,700 people, the traffickers acted "not out of an altruistic desire to aid escapes but simply to make money," said Romann.

The three dangerous voyages across the Mediterranean allegedly netted the traffickers an estimated $9.5 million, the police chiefs said.