WASHINGTON — The federal government sued a suburban Chicago school district Monday for denying a Muslim middle school teacher unpaid leave to make a pilgrimage to Mecca that is a central part of her religion.

In a civil rights case, the department said the school district in Berkeley, Ill., denied the request of Safoorah Khan on grounds that her requested leave was unrelated to her professional duties and was not set forth in the contract between the school district and the teachers union. In doing so the school district violated the Civil Rights Act of 1964 by failing to reasonably accommodate her religious practices, the overnment said.

Khan wanted to perform the hajj, the pilgrimage to Mecca in Saudi Arabia which every adult Muslim is supposed to make at least once in a lifetime if they are physically and financially able to. Millions go each year.

Khan started as a middle school teacher for Berkeley School District 87 — about 15 miles west of Chicago — in 2007. In 2008, she asked for almost three weeks of unpaid leave to perform the hajj. After the district twice denied her request, Khan wrote the board that “based on her religious beliefs, she could not justify delaying performing hajj,” and resigned shortly thereafter, according to the lawsuit filed in federal court in Chicago.

Berkeley School District compelled Khan to choose between her job and her religious beliefs, the lawsuit said.

The government asked the court to order the school district to adopt policies that reasonably accommodate its employees’ religious practices and beliefs, and to reinstate Khan with back pay and also pay her compensatory damages.

In November 2008, Khan filed a complaint with the U.S. Equal Employment Opportunity Commission, which found reasonable cause that discrimination had occurred and forwarded the matter to the Justice Department. The case is the first brought by department in a project to ensure vigorous enforcement of the 1964 act against state and local governments by improving cooperation between the Equal Employment Opportunity Commission and the department’s civil rights division.