Eleven members of the group are facing up to 8 years in prison, the tvp.info website reported.
The investigation is being carried out by the Border Guard on behalf of prosecutors in the north-central city of Bydgoszcz.
For the purposes of the scam, the crime ring registered new companies over the internet and then applied to authorities for permits to employ foreigners.
They produced addresses of hotels, farms and restaurants ostensibly interested in employing foreign workers, along with information about specific jobs and hourly rates.
However, company representatives, when interviewed by investigators, denied ever divulging such information, and also denied making any contact about hiring these foreigners.
Agnieszka Adamska-Okońska, spokeswoman for the Prosecutor's Office in Bydgoszcz, told reporters that "on the basis of documents swindled in this way from Polish institutions," thousands of foreigners "obtained visas in an illegal way and entered Poland and the European Union."
The foreigners came from various countries, including Ukraine, Russia and Belarus.
Visas were also issued to nationals of Moldova, Georgia, Kyrgyzstan, Serbia, Algeria, Angola, Bangladesh, Burkina Faso, the Democratic Republic of Congo, Gabon, Ghana, India, Cameroon, Kazakhstan, Congo, Morocco, Nigeria, Senegal, Egypt, Ethiopia, Kenya, Nepal, Rwanda, Ivory Coast, Uzbekistan, Philippines and Sri Lanka, tvp.info reported.
In all, Polish institutions received over 12,000 applications and statements containing false information, on the basis of which some 7,000 visas to enter Poland were obtained from Polish consulates, the website said.
In the course of the investigation, suspects were detained, with some of them placed under temporary arrest following a court order.
They were charged with being part of a criminal organisation and organising illegal border crossings.
These crimes carry a sentence of up to 8 years in prison, tvp.info reported.
(pm/gs)
Source: tvp.info