Saudi Arabia says the Muslim holy month of Ramadan will begin Tuesday across much of the Middle East.
Saudi state media reported that clerics had seen a crescent moon late Monday, marking the start of the celebration.
Clerics in Oman, however, did not see the crescent moon Monday and ordered the nation's faithful to begin Ramadan observances on Wednesday.
During the holy month, Muslims around the world are forbidden to eat, drink, smoke and have sexual activity in daylight hours (from dawn to dusk). Family and friends often gather at sundown to break their daily fast with a feast called "iftar."
Fasting the month of Ramadan is one of Islam's five pillars, including the belief in one God and all His Prophets and Scriptures, including the laws revealed to Moses, David, Jesus and Mohammed.
Muslims believe it was during Ramadan more than 1400 years ago that the words of the holy book, the Koran, were revealed to the prophet Mohammed. There are more than one billion Muslims worldwide.
Also in Ramadan, the ninth lunar month of the Islamic calendar, Muslims around the world take a step back from their daily routines and focus on community, charity and prayer.
Some information for this report provided by AP, AFP and Reuters.