Lanterns known in Arabic as Fanous Ramadan are displayed for sale at the Shorja market in central Baghdad, Iraq, on March 31, 2022. AFP
"The first day of Ramadan will be tomorrow" for Shia in Iraq, state media said Saturday, citing the office of the country's top Shia cleric, Grand Ayatollah Ali Sistani.
In neighbouring Iran, which like Iraq is majority Shia, as well as for Shia in Lebanon, Ramadan will also begin Sunday.
The starting date of the fasting month is determined by both lunar calculations and physical sightings of a new moon.
Traditionally, many Muslim-majority countries have followed dates set by Saudi religious authorities, but in recent years many have used their own astronomic calculations.
Sunni Muslims in Iraq, Lebanon and most Middle Eastern countries, including Saudi Arabia, the United Arab Emirates, Qatar and Kuwait, commenced the holy month on Saturday.
Jordan and Morocco, which are majority Sunni, and Oman, however, will begin on Sunday.
During Ramadan, observant Muslims refrain from eating and drinking from dawn to dusk, and traditionally gather with family and friends to break their fast in the evening.
It is also a time of prayers, during which Muslims converge in large numbers at mosques, especially at night.
In Asia, Afghanistan began Ramadan on Saturday, while Pakistan and India will begin on Sunday.
In Indonesia, the world's largest Muslim majority country, followers of the Muhammadiyah organisation began the holy month on Saturday, while those affiliated with the Nahdlatul Ulama, the country's largest Muslim association, will begin on Sunday.
The Eid al-Fitr holiday marks the end of the holy month.
Fasting during Ramadan is one of the five "pillars" of Islam.
The others are the profession of faith ("there is no God but God and Mohammed is his messenger"), the obligation to pray five times a day, charity, and the pilgrimage to Mecca at least once in a believer's lifetime.