It is the sort of invitation any poverty-stricken student would find hard to resist. "Do you have a professor who just can't stop talking about President Bush, about the war in Iraq, about the Republican party, or any other ideological issue that has nothing to do with the class subject matter? If you help ... expose the professor, we'll pay you for your work."

For full notes, a tape recording and a copy of all teaching materials, students at the University of California Los Angeles are being offered $100 (£57) - the tape recorder is provided free of charge - by an alumni group.

Lecture notes without a tape recording net $50, and even non-attendance at the class while providing copies of the teaching materials is worth $10.

But the initiative has prompted concerns that the group, the brainchild of a former leader of the college's Republicans, is a witch-hunt. Several targeted professors have complained, figures associated with the group have distanced themselves from the project and the college is studying whether the sale of notes infringes copyright and contravenes regulations.

The Bruin Alumni Association's single registered member is Andrew Jones, a 24-year-old former student who gained some notoriety while at the university for staging an "affirmative action bake sale" at which ethnic minority students were offered discounts on pastries.

His latest project has academics worrying about moves by rightwing groups to counter what they perceive to be a leftist bias at many colleges.

The group's website, uclaprofs.com, lists 31 professors whose classes it considers worthy of scrutiny. The professors teach classes in history, African-American studies, politics, and Chicano studies. Their supposed radicalism is indicated on the site by a rating system of black fists. The organisation denies on the website that it is conducting a vendetta against those with differing political views. "We are concerned solely with indoctrination, one-sided presentation of ideological controversies and unprofessional classroom behaviour, no matter where it falls on the ideological spectrum."

But in another posting, it is clear just where on the spectrum the group thinks the bias might fall. "One aspect of this radicalisation, outlined here, is an unholy alliance between anti-war professors, radical Muslim students and a pliant administration. Working together, they have made UCLA a major organising centre for opposition to the war on terror."