A $20 million class-action lawsuit has been filed by a UA chemistry professor against the Arizona Board of Regents, alleging a pattern of sex discrimination that she said resulted in her being paid less than male colleagues at the school’s College of Science.

The complaint alleges that compared to men, the University of Arizona underpays female faculty by tens of thousands of dollars per year, does not adequately promote women and denies equal access to work resources. It also claims the school retaliates against women who complain about discrimination.

The federal lawsuit was filed on behalf of Katrina Miranda, UA associate professor in chemistry and biochemistry, who joined the school in 2002, and all other female faculty members within the College of Science who have been with the school for at least three years, said Andrew Melzer, one of the attorneys representing Miranda.

University spokesman Chris Sigurdson said the school is not commenting on the lawsuit.

It was filed by the national civil-rights law firm Sanford Heisler Sharp, which is the same firm that filed the $2 million gender-based pay discrimination lawsuit against the regents in January on behalf of Patricia MacCorquodale, a former Honors College dean at the UA. Two additional female UA deans have joined that suit.