But in post-war Iraq there was lingering uncertainty over the start of the first holy fast after the fall of Saddam Hussein.
In Egypt, Jordan, Libya, Sudan and Yemen, the month-long dawn-to-dusk fast will start on Sunday, reports said.
Egypt's mufti, Shaikh Ali Juma made the announcement during a ceremony broadcast live on Egyptian state television.
Moon sighting disputed
The crescent moon marking the start of Ramadan could be seen by the naked eye at sunset, Shaikh Juma said.
Other authorities in neighbouring countries disputed the claim, saying it was impossible to sight the crescent in the region.
Palestinian dates: Traditionally,
Muslims break fast with the fruit
In the six Gulf monarchies, including Saudi Arabia the home of Islam's holiest sites in Makka and Madina, fasting will begin on Monday.
In Riyadh, the Judiciary Council said the crescent moon was not visible Saturday night, delaying the beginning of the fast until Monday, as in Kuwait, the United Arab Emirates, Bahrain, Qatar and Oman.
In Lebanon and Syria, the leaders of the Sunni and Shiite Muslim communities also said Ramadan would start on Monday.
Iraq curfew lifted
Iraq's most senior Shiite cleric, Ayat Allah Ali Sistani, said Ramadan would start on Monday.
But Sunni religious authorities in Baghdad had yet to announce the beginning of the fast by Sunday - meaning they will have start the month on Monday too.
However, the overnight curfew in effect in Baghdad for the past six months will be lifted on Sunday, in time for Ramadan, authorities announced.
"Coalition authorities have informed the Baghdad City Council that the curfew in Baghdad will be lifted beginning 4am on 26 October," Council Chairman Adnan Abd al-Sahib Hassan said on Friday.
In the Muslim tradition, Ramadan is a month of piety, alms-giving and fasting in order to instil the body and spirit with the rigours of abstinence.
Practising Muslims go without food, drink, smoking and sex from sunrise to sunset.
Fasting is one of the five pillars of Islam.
Religious authorities have denounced frequent gorging on food and recourse to light-hearted television programmes when the daily fast comes to an end with sunset.