POLICE say a Barcelona-based gang netted €4 million by selling fake diplomas to Spanish citizenship applicants.
The criminal organisation was broken up in simultaneous arrests co-ordinated by Europol.
35 people have been detained in Barcelona Province including the group leader.
A key gang member was also arrested in the United Kingdom.
The criminal crew falsified oral and written tests from the Cervantes Institute to obtain a DELE(Spanish as a Foreign Language) diploma which is a mandatory requirement for aspiring Spanish citizens.
The Institute is a worldwide non-profit organisation created in 1991 by the Spanish government to promote Spanish language and culture.
They organise citizenship courses and exams on behalf of the Ministry of Education.
Investigators identified 1,667 clients who paid the gang sums of between €1,000 and €4,500 each to get the bogus documents.
Most of the applicants were from Bangladesh, India, and Pakistan.
13 addresses were raided in Spain and the UK with hundreds of fake diplomas discovered by the police.
€50,000 in cash was seized along with an array of mobile phones and computer equipment.
An academy offered falsified test results to clients who did not have the required knowledge to pass the citizenship exam.
The academy manager was assisted by recruiters and intermediaries in reeling in customers.
The Policia Nacional has been working closely with the Cervantes Institute since 2018 over a variety of frauds.
In November 2020, 25 people were arrested across Spain for impersonating applicants during DELE examinations.