Teachers have ignored pupils' obvious cheating when signing off coursework, exam boards say.
Teachers have called for a return to more exam-based courses
Examiners complained of a lack of thorough checking, unusually similar work submitted by candidates and over-generous marking, a survey of their reports by the Times Educational Supplement suggests.
One analysis accuses teachers of signing authentification statements "with a photocopied signature" for the intermediate GNVQ in information and communication technology run by the Edexcel board.
Candidates for its land and environment GNVQ are said to have submitted work downloaded from the internet.
'Clear code of practice'
The AQA board noted large amounts of "copying" in A-level sociology coursework and questioned how "independent" some GCSE history projects had been.
The findings come as teachers' unions are calling for less coursework to reduce the load on their members.
George Turnbull, spokesman for the exam boards' joint council, said: "There's a code of practice and it is quite clear to the students and teachers what they can and cannot do.
"If we have a teacher who breaks the rules, there is no other description for it than cheating.
"If they are teaching unprofessionally, they face penalties, both professionally and possibly in the courts."
Some teachers have claimed that pressures of time, rather than a desire to cheat, lead to unacceptably poor coursework checking.
But Mr Turnbull said: "Such behaviour could undermine the credibility of the qualifications and those who gain them.
"We have every confidence in the marks we have awarded for coursework. We maintain the highest professional standards.
"There are thousands of people working in this area, so, unfortunately, there will be varying degrees of professionalism."