The nation's largest public school system will observe the two most important Muslim holidays starting next fall, a policy change hailed Wednesday by Islamic leaders in New York City.

Under the new policy, the city's 1.1 million-pupil public school system will close on Sept. 24 for Eid al-Adha, which is also known as the Festival of Sacrifice. The holiday of Eid al-Fitr, marking the end of Ramadan, will be observed during summer school in 2016.

"Hundreds of thousands of Muslim families will no longer have to choose between honoring the most sacred days on their calendar or attending school," Mayor Bill de Blasio said in his announcement.

Muslim leaders welcomed the announcement.

"After years of advocating by New York City's Muslim community, Muslim public school students will finally and thankfully no longer be penalized for observing their religious holidays," said Zead Ramadan, a board member of the Council on American-Islamic Relations.

Linda Sarsour, a Muslim community advocate and public school parent who joined de Blasio for the announcement at a school in Brooklyn, said, "This is what New York City is all about — recognition, inclusion and respect."

Estimates of the number of Muslims living in New York City vary from 600,000 to 1 million.

Community leaders have long urged adding the two Muslim holidays to the school calendar, and the City Council passed a resolution supporting the change in 2009.

Former Mayor Michael Bloomberg opposed making the change but de Blasio and the other major candidates who campaigned to succeed Bloomberg in 2013 all said they would implement it.

The new calendar will keep the total number of school days unchanged at 182: the state-mandated 180 plus two more in case there are snow days.

New York City public schools have long closed for major Jewish holidays such as Rosh Hashana and Yom Kippur as well as the Christian holidays of Christmas and Good Friday.

Other public school systems that have moved recently to observe Muslim holidays include those in Waterbury, Connecticut and Frederick County, Maryland.