Muslims began observing the holy fasting month of Ramadan on Sunday with Islamic leaders again concerned about entrenched conflicts as jihadists issued threats from Indonesia to Somalia.
Ramadan is sacred for the world's estimated 1.6 billion Muslims because it is during that month that tradition says the Koran was revealed to the Prophet Mohammed.
The faithful fast from dawn to dusk, and abstain from eating, drinking, smoking and having sex during that time as they strive to be more pious and charitable.
In that spirit the Jeddah-based Organisation of Islamic Cooperation launched a joint appeal with the Arab League for a ceasefire in Syria, where a deadly conflict has raged unabated for more than three years.
"The appeal is to stop the bloodshed of Syrians and alleviate their suffering and allow relief organisations to carry out their duties and provide urgent humanitarian assistance," a joint statement said.
The call came as Saudi King Abdullah, whose country is home to Islam's holiest sites, sharply criticised religious extremists and vowed not to let "a handful of terrorists... terrify Muslims".
Islam is "religion of unity, fraternity and mutual support" but some people "lured in by false calls... are confusing reform with terrorism", the monarch said.
"Their goal is to sow discord among Muslims," he said in an apparent reference to insurgents from the Islamic State of Iraq and the Levant (ISIL) active in Syria and Iraq.
The radical jihadist group has spearheaded an offensive by Sunni militants in Iraq since June 9, wresting control of northern cities and capturing vast swathes of territory.
Its goal is to set up an Islamic state that straddles Syria and Iraq, and on Sunday ISIL took a step in that direction by announcing the establishment of a "caliphate".
Meanwhile Al-Qaeda-linked Shebab militants warned they would step up attacks during Ramadan in the Somali capital Mogadishu, where officials deployed dozens of heavily armed police to deter violence.
Top commander Sheik Ali Mohamed Hussein said "Mujahedeen fighters will scale up strikes on the enemy" because "jihad must be intensified during the holy month of Ramadan".
Somali President Hassan Sheik Mohamud said his government has a plan dubbed "break your fast in peace" to deter violence, while the police chief spoke of a "Ramadan security plan".
- Word Cup threats -
In Indonesia, home to the world's biggest Muslim population of about 225 million, hardliners pledged to raid bars that sell alcohol or stay open late.
The Islamic Defenders' Front would "monitor any sinful activities in entertainment places, cafes and bars during Ramadan", said Salim Alatas, the group's chief in Jakarta.
"If law enforcement officials do nothing about immoral activities, we will do anything we can to stop them, using our own methods."
But the threats did little to deter people in the football-crazy nation, where most practise a moderate form of Islam, from heading out to catch the latest World Cup action.
Bars that remained open in Jakarta were packed with locals and expatriates late Saturday and early Sunday.
"For me, the fasting does not really affect my enthusiasm to watch the World Cup," said Intania Permata, a 22, who was watching the Brazil versus Chile nail-biter at a South American bar and restaurant.
Ramadan was also observed in Afghanistan, Malaysia, Pakistan, Sri Lanka and the Philippines, with politics and unrest very tangible in the background.
For half a million Pakistanis displaced by a military offensive in the country's north, the prospect of fasting amid severe food shortages and soaring temperatures has sharpened anger towards the government.
Taxi driver Shakeeb Ur Rehman, 40, said the military bulldozed his house and his car was destroyed in a bombing.
"I'm homeless and seriously worried about fasting in this hot weather. I think religious scholars should issue a decree allowing us to be exempt," he said.
Sri Lanka's Muslims were expected to observe a low-key Ramadan amid fears of renewed Buddhist extremist attacks after four people were killed in religious riots this month.
In the predominantly-Catholic Philippines, the Muslim minority was observing its first Ramadan since the government signed a peace deal with the largest Islamic rebel group after decades of conflict.