Muslims in Saudi Arabia and at least 14 other countries will celebrate on Sunday the first day of the Eid al-Fitr festival, which marks the end of the Islamic fasting month of Ramadan.
Saudi Arabia, home to Islam's holiest sites, announced that Saturday was the final day of Ramadan.
Similar official announcements were made in Egypt, the United Arab Emirates, Bahrain, Qatar, Jordan, Kuwait, Lebanon, Libya, Palestine, Syria, Sudan, and Yemen.
Indonesia, the world's most populous Muslim-majority country, as well as Malaysia also said they would celebrate the first day of the feast on Sunday.
However, Oman will celebrate the first day of Eid al-Fitr on Monday, the official Omani news agency reported.
The beginning and end of Islamic months are determined by the sighting of the new moon.
Early on the first day of Eid al-Fitr, Muslims perform a special prayer at mosques.
During the three-day festival, children wear new clothes and receive cash gifts. Relatives and friends, meanwhile, exchange visits and eat special delicacies.