CHAPEL HILL, N.C. — Federal authorities are investigating an incident at the University of North Carolina at Chapel Hill in which an instructor sent an e-mail to her class accusing a conservative student of "hate speech" for a statement he made about homosexuals.

The Department of Education's Office for Civil Rights told the school last week that the investigation would determine whether the teacher's actions amounted to harassment.

Education Department spokesman Rodger Murphey said several people filed complaints about an exchange last month in an English class during which a student said he opposed homosexuality. Instructor Elyse Crystall sent an e-mail to the class criticizing the student, saying his comment "constitutes 'hate speech' and is completely unacceptable."

She referred to the student by name, calling him "a white, heterosexual, christian male" who "can feel entitled to make violent, heterosexist comments and not feel marked or threatened or vulnerable."

Crystall apologized today in another e-mail, saying her earlier message "crossed a line and inhibited free discussion."

University officials said they were monitoring the class to ensure students' free speech.

Faculty members passed a resolution on March 26 committing themselves to "intellectual independence, nondiscrimination on the basis of, among others, race, sex and sexual orientation, free speech and expression."