Millions of Muslims around the world will mark the start of the holy month of Ramadan on Monday, a time marked by intense prayer, dawn-to-dusk fasting and nightly feasts.

Saudi Arabia's state TV announced the new moon of Ramadan was spotted Sunday evening. Local media in Indonesia, the world's most populous Muslim country, also said Muslims there would begin fasting Monday.

Muslims follow a lunar calendar and a moon-sighting methodology that can lead to different countries declaring the start of Ramadan a day or two apart.

The faithful spend the month of Ramadan in mosques for evening prayers and break their fast as the Prophet Muhammad did around 1,400 years ago, with a sip of water and some dates at sunset. During the day they abstain from eating and drinking.