(Reuters) - A black woman who joined protests at New Jersey's Kean University over racial conditions on college campuses was sentenced on Friday to 90 days in jail for making anonymous false threats against black students in an attempt to stoke protests, prosecutors said.

Kayla McKelvey, 25, pleaded guilty in April to a single charge of creating a false public alarm after making the threats on social media, the Union County Prosecutor's Office said in a statement.

McKelvey was also sentenced to five years of probation and will be required to pay more than $82,000 in restitution among other conditions, the prosecutor's office said.

Prosecutors said McKelvey was participating in a rally on racial issues on Nov. 17 and left the event early to post racist threats of violence on social media.

"I will kill all the blacks tonight, tomorrow and any other day if they go to Kean University," a tweet read, prosecutors said.

McKelvey then returned to the rally and tried to raise awareness of the fake threats, which prosecutors said prompted many students to not attend class in the following days and cost tens of thousands of dollars in additional security for the campus.

An attorney for McKelvey could not be immediately reached for comment on Friday.

A Linked In account under McKelvey's name describes her as a past president of Kean's Pan African Student Union and a former homecoming queen at the school.

Kean University, which sits about 10 miles southwest of Newark, is one of many universities where students staged demonstrations and walkouts last year in support of students at the University of Missouri, where the school president resigned after protests over his handling of racial issues.

Shortly after those protests proliferated, several men across the country were charged with making actual threats on social media to kill black students.

(Reporting by Curtis Skinner in San Francisco; Editing by Cynthia Osterman)