The vice-president of Bulgaria's governmental education committee has accused 250 international universities of operating "illegally" in the country.
Dimitar Kamburov said a report on education in the country found that a huge number of foreign universities with offices in Bulgaria - including the University of Portsmouth - were teaching students without the accreditation needed under Bulgarian law.
Universities must apply to the Bulgarian Accreditation Committee, which checks standards of teaching, for endorsement to teach and award recognised qualifications.
Nikolay Kolev, deputy dean at the accredited Bourgas Free University, said:
"Students in Bulgaria are not getting the level of education they are entitled to because of the number of places of higher education that are operating illicitly."
A spokesman for the International University in Sofia, with which Portsmouth has a franchise, said its programmes met Quality Assurance Agency requirements and were in line with European Union legislation, which was accepted by Bulgaria as an accession state.