Students at the University of Southern California filed two class-action lawsuits last week in an attempt to nullify repeated tuition increases over the past three years.

The two lawsuits, one representing law students and one representing undergraduates, ask for almost $5 million in reparations. Tuition at USC has increased from $1800 to $2640 since 1970 and is expected to rise again next year.

The students claim that the trustees broke an implied contract with them by approving tuition increases without first consulting any members of the student body, a spokesman for USC's newspaper, The Daily Trojan, said yesterday.

The suit, in addition to demanding refunds, asks that there be no further tuition increases without prior consultation with student representatives.

The university has 30 days to enter a plea in Superior Court, the spokesman said, although the case may take up to two years to come to trial.

Members of the Tuition Action Committee, which is responsible for the filing of the lawsuits attempted first to rotate through the treausurer of the university. All alternatives and compromises were ignored," the spokesman said. "This university would not even give its students access to its financial records.

Hale Champion, Harvard's financial vice-president, said yesterday that no such action had been initiated at Harvard. "Obviously, everyone is concerned over tuition increases," he said. "But we've explained it and beyond those explanations there is no matter pending on the subject.