Millions of Muslims will begin their month-long fast on Saturday after more than 30 countries declared the start of Ramadan.
Saudi Arabia was among the nations to announce on Friday that the 'holy month' would begin on May 27. Fasting will begin a day later, on May 28, in Bangaldesh, Pakistan and India.
Iran will also observe the fast from Saturday, despite differences on the start date in previous years.
The Islamic month of Ramadan is announced in each country following a local sighting of the new moon.
One of the five pillars of Islam, Muslims abstain from drinking, eating, smoking and having sex during daylight hours throughout the month.
Ramadan 2017 is expected to end on June 24, when Muslims will celebrate Eid al-Fitr.
