Universities' growing reliance on unqualified, badly paid postgraduates to teach students is too informal and poorly controlled, according to the Political Studies Association.
The association is calling on teaching unions and universities to consider establishing national minimum levels of pay, conditions and training for postgraduate teachers.
It has carried out a survey that paints a picture of inconsistency and exploitation in postgraduates' status, pay and conditions. It reveals, for instance, that wages range from £9.90 to £43 an hour.
Report author Sean McGough said that although the received wisdom was that postgraduates taught only first-year undergraduates, in reality 75 per cent were teaching second-year undergraduates and one in ten was teaching masters students.
"Nearly half of all postgraduates surveyed are spending more than ten hours a week on teaching and class preparation, while one in four is teaching classes of between 16 and 40 students," he said.
"Teaching qualifications are only stipulated as a prerequisite in 24 per cent of appointments. Although 86 per cent of graduates then receive some form of university teacher training, fewer than one in ten of the courses leads to a recognised qualification."
The association surveyed 44 politics department heads and 100 politics graduate teaching assistants.
The findings have gone to unions and will go to the department heads conference today.
Postgraduates were generally positive about their teaching experience but 90 per cent felt the time it took up and the pressure it added impeded their research.
Mr McGough, a PhD student at Birmingham University's department of political science and international studies, said the problem was compoundedby poor mentoring services, stark differences between the provision of teaching resources for full-time staff and postgraduates and problems with teaching supervision.
"There seems little attention to the levels of teaching undertaken, or for the general lack of teaching qualifications that postgraduates possessed either prior to or during their tenure as teachers," Mr McGough said.
"Unions have postgraduate sections but postgraduates are always under pressure to fit in, so they are unlikely to protest. I would like to see unions and universities get together to lay down minimum standards."
The report, The Future of Political Studies: Teaching in the New Millennium , was funded jointly by the PSA and the Centre for Sociology, Anthropology and Politics.