PROVIDENCE, R.I. (AP) — Teachers in Cranston, Rhode Island, have filed a lawsuit against the city's school department after their requests to observe Good Friday were denied in a move they say violated their civil rights.

About 200 teachers contacted the union to report that they were being prevented from taking the day off, although they had provided more than the contractually required 24 hours' notice, said Liz Larkin, president of the Cranston Teachers' Alliance.

However, teachers' requests to observe the Jewish holiday of Rosh Hashanah in the fall were approved, Larkin said.

"That's my big concern here, is equity," Larkin said.

School superintendent Judith Lundsten said in a statement Tuesday that the teachers' contracts specify they may take a holiday if they are required to attend religious services during the school day. Because Good Friday has "no required services," Lundsten said, their requests were denied.

Lundsten said requests to observe Rosh Hashanah, on the other hand, were approved because that holiday "does not allow work."

"From our perspective, this is about a calendar that was agreed upon and passed by the school committee nine months ago," she said.

The suit filed Monday is the latest legal battle over religion in Cranston schools.

In January 2012, a federal judge ordered a prayer banner at a Cranston high school removed after the state chapter of the American Civil Liberties Union sued on behalf of student Jessica Ahlquist, an atheist. The judge's ruling that the banner was unconstitutional set off a storm of criticism of Ahlquist, who received anonymous threats and scorn from lawmakers.

Kevin Daley, the attorney representing the union, said the teachers' collective bargaining agreement allows them to take up to two days off per school year to observe religious holidays. Daley said the contract does not specify restrictions on religious observances.

"They can take them if there are required services that take place during the school day," Daley said. "And Good Friday is regarded by Christians as certainly the most solemn of days of the church calendar."

The school committee voted in June to hold classes on Yom Kippur, Rosh Hashanah and Good Friday. Up until then, these holidays had been observed by schools in Cranston.

Larkin said she would like the committee to reinstate the holidays.

"This is the first year in many in decades that they have not been in the calendar," Larkin said.

But Lundsten said that the teachers negotiated an increased hourly wage in exchange for giving up certain paid holidays, including Good Friday.

Tim Ryan, executive president of the Rhode Island Schools Superintendents Association, said the school committee was trying to do the right thing by rescinding the holidays, fitting more school days into the calendar.

"We've had challenging weather," Ryan said. "Every day is precious."

Good Friday is a "traditional holiday," Ryan said, rather than an "official holiday."

Larkin said she is fascinated that the school committee, which fought to keep the prayer banner up, would vote to rescind the religious holidays.

But Daley emphasized that the purpose of the lawsuit isn't to reinstate the holidays.

"We're asking that my clients be permitted to exercise their contractual rights by taking these religious observation days," he said.

A hearing has been scheduled for March 30.