Reports of robbery, assault and motor-vehicle theft on college campuses rose last year, but there were fewer burglaries and murders than a year earlier, according to a survey of 774 schools.

The Chronicle of Higher Education, analyzing annual security statements filed by the schools, reported Saturday there were 1,353 on-campus robberies in 1993, up about 12 percent from 1992.The colleges reported 3,224 cases of aggravated assault, up from 3,141, and 7,350 motor-vehicle thefts, up from 7,159. Burglaries dropped about 4 percent, to 21,478, the newspaper said, while the number of murders fell by one, to 17.

The colleges also reported 466 rapes and 448 forcible sex offenses, but the Chronicle said those figures could not be compared with data from the previous year because of changes in the definition of sex crimes.

Federal law requires the schools to prepare annual security reports and distribute them to students and staff. The newspaper said there is confusion among college officials about the requirements of the law, and critics say some schools deliberately under-report crime on their campuses.

"Rather than promote reporting, the law has promoted rather clever maneuvering about how incidents get reported," Patricia A. McGuire, president of Trinity College, told the newspaper. "By underreporting crime, we are increasing the likelihood that the quality of safety on campus is deteriorating, not improving."