The decision to celebrate the festival on Sunday came following the sighting of the moon of Shawwal, the month following Ramzan.
Official Twitter for Haramain, which gives updates about Makkah and Madinah, announced the sighting of the moon.
"The moon has been sighted in Saudi Arabia. Eid-ul-Fitr will be celebrated tomorrow, Sunday 25th June 2017," it said.
In Dubai, the Dubai Media Office sent out a tweet announcing the beginning of the month.
"Eid Mubarak. UAE announces tomorrow 25 June 2017 as the first day of Eid ul-Fitr," the tweet said.
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Meanwhile, Oman's Ministry of Endowments and Religious Affairs has announced that Monday, June 26, will be the first day of Eid ul-Fitr after failing to sight to crescent moon in Muscat.
Bangladesh, Pakistan, India will be sighting the moon tomorrow. These countries started Ramzan on May 28 and so tomorrow will be the 29th of Ramzan for them.
Eid ul-Fitr, which means "festival of breaking the fast", marks the end of the Muslim holy fasting month of Ramzan.
Turkey and Muslim communities in North America, Europe and Australia had previously announced they would celebrate Eid ul-Fitr from tomorrow based on astronomical calculations.