Muslims in several Middle Eastern countries have begun observing the holy month of Ramadan.
Religious authorities in Saudi Arabia, the birthplace of Islam, said the new crescent moon was sighted Monday night, signaling the start Tuesday of a month of spiritual reflection.
Clerics in Oman did not see the crescent moon and say their observances will begin Wednesday. Iran also will start the holy month Wednesday.
It was during this period more than 1,400 years ago that Muslims believe the words of their holy book, the Quran, were revealed to the Prophet Mohammed.
During Ramadan, Muslims abstain from eating, drinking, smoking and having sexual relations from sun up. They may only break their fast at sundown.
President Bush has sent Muslims around the world a message of greetings to mark the beginning of Ramadan in the United States.