University of California, Santa Cruz has fired 54 graduate students who have been striking for higher wages by refusing to turn in undergraduate students' grades.

The students were dismissed Friday after failing to comply with a university-imposed deadline to submit the grades and were told they were being fired for insubordination and "abandonment of job responsibilities," according to a notice from university officials posted on the striking students' website.

UC Santa Cruz spokesman Scott Hernandez-Jason said in a statement that 96% of grades were submitted and the "vast majority'' of graduate students have returned to work. He called out the 54 students for "withholding grades for undergraduate students in a way that unfairly impairs their education.''

About 200 teaching assistants decided in December to withhold fall quarter grades to demand an increase in pay of $1,412 a month to afford the area's high cost of living. The strike is considered a wildcat strike because it is not endorsed by the union that represents UC's graduate student employees, who are working under a four-year contract that expires in 2022.

The students escalated the grade strike in early February to a full work stoppage by refusing to teach, hold office hours, conduct research or post grades. Seventeen students were arrested at a campus protest Feb. 12, and UC Santa Cruz and the UC president published a series of letters online warning student workers they would be disciplined if they failed to submit grades.

About 30 other students who had yet to secure spring teaching jobs were told they would not be eligible for the positions, the protesters said. UC Santa Barbara graduate students voted Monday for a full strike, and UC Davis students decided Thursday to withhold student grades for the winter quarter until the university raises their housing supplement.

Students across the 10 UC campuses have held rallies in support of student workers at UC Santa Cruz. Hernandez-Jason said UC Santa Cruz's administration has worked to hear and address teaching assistants' concerns.

This week, the university offered a $2,500 stipend and two temporary housing assistance programs, but graduate students said the promise is inadequate and not legally enforceable.