Riyadh: Muslims around the world enter Ramadan, but even worshippers in the same country can begin fasting on different days because of disputes over how and where the new moon is sighted.

The timing of Ramadan, when the faithful fast from dawn until dusk, varies in different Muslim countries depending on the sighting of the new moon, according to the Islamic lunar calendar that binds the world's one billion Muslims. Reasons for the discrepancy range from the political to the esoteric.

Most Gulf countries follow Saudi Arabia. Other countries such as Egypt with their own centres of learning are sure to establish the new moon for themselves.

"It is odd. There is a halo of politics," said Saudi preacher Abdul Aziz Al Qassem.

The Islamic Society of North America (ISNA) advises Muslims to follow the sighting in that part of the world, but some mosque imams will follow Saudi Arabia.

This year, Saudi Arabia and most Gulf countries began fasting yesterday. Oman and Egypt begin today, while Libya, to the west of Egypt, has insisted on Saturday.

"People in Arab and Muslim countries are turning to Libya to know when Ramadan begins," Libyan leader Muammar Gaddafi said this week, championing what he called Libya's 'correct Islam'.

One key dispute is whether to use the naked eye to which Saudi Arabia has stuck rigorously or astronomical calculations, strongly promoted by North American groups.

Traditionalists say viewing must be done by humans, as it was in the time of the Prophet, but modernists say that was only because there was no better means of knowing at the time.

Islamic scholars in North America have already fixed Ramadan and the Eid Al Fitr holiday at its end for the next five years.

"We are saying that the actual sighting with the naked eyes is not required. If the moon is born and enough time has passed after conjunction to make the moon visible, then we accept it," the Fiqh Council of North America said.

In Pakistan, the sighting of the moon is decided by the Reut-e-Hilal Committee, a government-appointed panel of clerics.

However, clerics in northwest Pakistan often say Ramadan and Eid Al Fitr are to begin before the day announced by the authorities.

In Indonesia, the world's most populous Muslim country, few dared to break with the government line under the iron-fisted rule of former President Suharto. Since he fell from power in 1998, a plethora of groups has emerged with their own edicts.

The 40-million strong Nahdlatul Ulama, Indonesia's largest Muslim group, follows the naked-eye principle, while the second biggest, the 30-million strong Muhammadiyah, uses calculations.

"This year it looks like we have an agreement," said Ma'aruf Ameen, deputy chairman of an umbrella group of clerics, referring to the government's declaration that Ramadan begins today.

"Some think the world should only have one guide, so they follow what Saudi Arabia says," Ameen said.

The confusion is more serious over the month of Dhul Hijja when two million Muslims congregate in Saudi Arabia for the Haj pilgrimage to Makkah and the Eid Al Adha festival.

Most Muslims worldwide follow the lead of Saudi Arabia because that's where the Haj rites take place.

Al Qassem said Saudi religious authorities were moving towards a new system that uses both the traditional and modern methods.

"This is a problem that affects people in their daily lives. If you have a reservation for a plane, you can't wait until someone somewhere says he thinks he saw the new moon," he said.