Portugal has detained 67 suspects over the charge of identity document fraud, the country's Foreign and Border Service announced on Monday.
The detentions were carried out on Saturday after a series of investigations into 34 language schools in collaboration with the Education Ministry, the service said in a statement.
Some 2,075 people have been checked during the investigation, among whom 67 were found with forged documents while attending exams.
All the detainees are suspected of "using others' documents," the service said.
According to the law, the Portuguese government grants citizenship to foreign applicants who have passed oral and written exams on the Portuguese language.