NEW HAVEN, Conn. (AP) — Police have charged 23 Yale University graduate students with misdemeanors for blocking New Haven streets during a protest against sexual harassment at the university.

Authorities say protesters caused the closure of three major intersections during peaceful demonstrations Thursday morning. Police said 20 people voluntarily agreed to be cited for disorderly conduct and three chose to be taken into custody.

The demonstrators also protested what they called the university's refusal to negotiate with the new graduate student labor union. Graduate students who also teach voted to unionize in February and have staged other protests.

Protesters cited a Yale survey that found 54 percent of female graduate students experienced sexual harassment.

Yale officials say the university already takes sexual harassment allegations seriously and has policies and procedures to address the problem.