An overhaul of GCSE coursework has been damaging to modern foreign language classes, according to a report by the exams regulator.
It reveals teachers' concerns that the move to axe traditional coursework and replace it with "controlled assessment" has put pupils' learning at risk.
Teachers have less time to teach and are forced to concentrate on the topics and language that students will need to use in their controlled assessment work at the expense of other areas, the Ofqual report says.
The study, based on interviews with modern foreign language (MFL) teachers, comes after a report last year raised concerns about the impact of controlled assessment on languages. The new study reveals that most of those questioned had "significant concerns" about the new system, with some calling for a return to traditional coursework.
Controlled assessment was introduced around three years ago, amid concerns about cheating and plagiarism. Under the new system, GCSE pupils complete coursework under strict classroom supervision, rather than doing it at home.
Ofqual's report found that most MFL teachers believe that teaching time has been reduced, and that learning has been narrowed by the new system.
"Teachers feel that they have no alternative but to concentrate their teaching on the topics and language that are part of controlled assessments at the expense of other topics, and to focus on the vocabulary and structures their students need to gain high marks in the assessments rather than teaching more broadly," the report says.
Some of those questioned told Ofqual that students' reading and listening skills were suffering because they were focusing more on what they need to do for their controlled assessments.
The report does not draw conclusions but Ofqual said that the findings will be part of a wider review into controlled assessments in all GCSE subjects.
It comes as a study by Cambridge Assessment found that almost half of teachers believe that the new-style coursework has cut the risk of plagiarism. But there were concerns that the risks have not been eliminated and that there is the potential for abuse of the system by teachers and students.