GAZA CITY, Gaza Strip — Over a billion Muslims around the world began observing the holy month of Ramadan on Wednesday, with the dawn-to-dusk fast posing a particular challenge for the devout in the sweltering Middle East summer.

A heat wave has covered much of the region, putting even the most ardent believers to the test.

In some places -- such as Egypt, Lebanon and the Gaza Strip -- the hardship of abstaining from food, drink and cigarettes for 15 hours was compounded by frequent power outages.

"I'm not sure if I can continue fasting," lamented Ismail Abu-Hasweh, 28, standing in line at a government office in Amman, Jordan. "I'm a chain smoker and I feel lightheaded because I didn't smoke or drink my coffee," he added, removing dark sunglasses to show his red eyes.

Ali Shishi, 30, working in a downtown public garden in Damascus, Syria, said he planned to work a full shift. "My fasting will not be accepted by God if I quit my work," he said. But his manager told him just before noon he should stop working because it got too hot.

In Cairo, barber Mohammed Abdo said working and reading the Qur'an, the Muslim holy book, keeps his mind off his stomach.

The start of Ramadan changes every year, based on the sighting of the new moon at the start of the lunar month. The calculation can be a show of regional clout, with senior clerics across the conflicted Mideast and the two main sects of Islam often disagreeing.

This year, most Sunni Muslims began fasting Wednesday, while Shiite Muslims in Iran, Iraq and Oman are to begin observances Thursday. Lebanon's Shiites were split.

By midday, temperatures reached the high 90s in degrees Fahrenheit (high 30s in degrees Celsius), and even topped 100 Fahrenheit, or 38 Celsius, in many parts of the Middle East.

Some took steps to ease the burden of fasting in the heat.

The governments in Jordan, Lebanon and the Palestinian territories reduced the work day of civil servants from eight to six hours. Some construction workers in Lebanon struck deals with their employers to work for a few hours at night, instead of during the day.

In the United Arab Emirates, the top religious authority issued a religious edict, or fatwa, allowing labourers to eat if it is too hot or conditions are too difficult to fast. Religious officials issued the decision in response to a question from an oil rig worker.

"God does not burden any soul beyond what it can bear, and God knows best," the fatwa said.

In Cairo, Sheik Eid Abdel-Hamid, a preacher at the Al-Azhar Mosque, told the daily al-Gomhuria that those engaged in hard physical labour can break their fast and make up for it later.

In Egypt, the West Bank and Gaza, the clock was moved back an hour. This does not change the duration of the fast, but eases it by allowing people to break their fast earlier in the evenings.

Ramadan is a time of heightened religious fervour and giving to the poor.

In impoverished Hamas-ruled Gaza, where a majority of 1.5 million residents depend on food handouts, the Social Affairs Ministry planned to distribute food to 13,000 families of unemployed workers and prisoners held by Israel. The ministry said it also received 75,000 food parcels donated by charities abroad.

Egypt's ruling party, which faces parliamentary elections in a few months, announced it is distributing 1 million Ramadan gifts as an expression of social solidarity.

In Gaza, power outages were one of the biggest concerns during Ramadan.

In the worst periods, electricity is off for 12 hours, on for four, then off again for 12. The blackouts are caused by an overburdened grid, unrepaired damage from Israeli military offensives and a dispute between the Islamic militant Hamas and the Western-backed Palestinian government in the West Bank over who should pay for fuel for Gaza's only power plant.

Gaza housewife Tharwa Suboh said the power cuts make Ramadan observances very difficult because the family does not have a fuel-powered generator.

"It is very hot ... and now we are fasting, and don't even have power to run an electric fan," said the mother of five girls, ages nine to 16, who all observe Ramadan. She said she has to shop every day, instead of once a week, because she cannot refrigerate food.

"In our prayer, we will ask God for forgiveness, but also to take revenge against all the people who are behind our suffering due to the power cuts," said Suboh, 38.

Short blackouts have also been common in areas of Egypt, in part because of increased electricity consumption during the summer heat. The government has banned people from using public supply outlets to hang Ramadan ornaments.

Egyptian media said the electricity ministry has declared a state of emergency and plans to start up two new power stations to deal with the extra load during Ramadan. Consumption is expected to rise because people stay up into the night.