CHICAGO, May 4 (Reuters) - Dozens of families on Wednesday sued two federal agencies and a suburban Chicago school district over a policy they said disregards student privacy and safety by allowing transgender students to use bathrooms that correspond with their gender identity.

Fifty-one families in the Palatine, Illinois, area sued the U.S. Department of Education, the U.S. Justice Department and Township High School District 211 for agreeing last December to provide a changing area in the girls' locker room for transgender students. The lawsuit seeks an injunction to prevent enforcement of that agreement.

That deal stemmed from a complaint filed in 2013 by the American Civil Liberties Union of Illinois on behalf of a transgender student who was born male and identifies as female.

Superintendent Dan Cates said in a statement the school district's deal with federal officials "provided workable solutions protecting the privacy and honoring the dignity of all students." He said there had no reports of issues since the deal was implemented.

Dorie Turner Nolt, a spokeswoman for the Education Department, said the agency would not comment on pending litigation. Officials with the Justice Department could not be reached.

Legal battles over bathrooms are being fought across the country as school officials, lawmakers and Republican presidential candidates debate whether transgender people should be allowed to use restrooms that match their gender identity instead of their birth sex.

Wednesday's lawsuit, representing 73 parents and 63 students, contends the Education Department is unlawfully redefining terms of the Title IX Act, a federal statute that prohibits sex-based discrimination by schools receiving federal funding. The plaintiffs also said the federal agency is forcing its political will on school districts.

The lawsuit was filed by attorneys for the Alliance Defending Freedom, which advocates for conservative positions on religious liberty.

"Every day of the school year a certain number of girls have to share the locker room space with a biological male and it makes them incredibly uncomfortable, stressed and anxious about the things going on in their school day," Jeremy Tedesco, an attorney for the families, said at a news conference in U.S. District Court in Chicago.

The Justice Department told North Carolina's governor on Wednesday a new state law limiting restroom access for transgender people violates the U.S. Civil Rights Act.

Last month, a U.S. appeals court ruled for a Virginia transgender student seeking access to the bathroom of his gender identity.

Chicago's public school system said Tuesday it would allow transgender students to use restrooms and locker rooms that correspond with their gender identities.

Edwin Yohnka, a spokesman for ACLU of Illinois, in an email called Wednesday's lawsuit "a sad development by groups opposed to fair and humane treatment of all students." (Additional reporting by Ben Klayman in Detroit and Julia Harte in Washington; Editing by Alistair Bell)