Saudi Arabia, home of the holiest shrines in Islam in Mecca and Medina, has announced that the fasting month of Ramadan will start on Thursday.

The kingdom's supreme court ruled on Tuesday evening that the Islamic calendar month of Shaban, which precedes Ramadan, will end on Wednesday, meaning Ramadan will begin the following day, the official Saudi Press Agency reported.

Authorities earlier on Tuesday called on residents to try to spot the crescent moon that marks the start of Ramadan, but it was not visible, state media said.

Other Sunni-majority countries including Egypt and Qatar also announced that Ramadan would begin on Thursday, as did officials in the Palestinian territories.

Authorities in Jordan, Algeria and Morocco meanwhile said a decision would be taken on Wednesday as to whether Ramadan would start on Thursday or Friday.

The daytime fasting month of Ramadan is one of the five pillars of Islam.

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.

Fasting is strictly observed in Saudi Arabia, with restaurants closed until sunset iftar meals.

It is also a time of prayers, with the faithful converging in large numbers at mosques, especially at night.

The starting date of Ramadan, the holiest Muslim month, is set by both lunar calculations and physical sightings to determine the beginning of a new month. (AFP)