"Syria is bleeding," a message said.
In Libya, rebel fighters locked for months in deadly battles with strongman Moamer Kadhafi's regime, told AFP there was no question of stopping what they see as their march on Tripoli.
"Yes, Ramadan is beginning but we will continue to fight," said Colonel Juma Brahim, head of the rebel fighters' operational command in the Nafusa region, from his command post in Zintan.
"If it's war and we're tired, we'll eat. But if we remain in a defensive position, we will fast. God is with us," said Hatem al-Jadi, a 24-year-old fighter in the western desert hamlet of Gualish, south of Tripoli.
But in Cairo, where massive streets protests overthrew the 30-year rule of president Hosni Mubarak in February, demonstrators camped out at the emblematic Tahrir Square suspended their sit-in for Ramadan.
Mubarak is due to face trial on Wednesday along with his two sons, a key business associate, his former interior minister and six security officers on charges of murder and corruption.
Egyptian youth protesters who brought down his regime in a swift 18 days of protests said they will return to Tahrir Square to press for reforms after the holy month is over.
Activists have been occupying the square since July 8 to denounce what they say is the handling of the transition by the military rulers who have been running the country since Mubarak's ouster.
But protesters in Yemen camped out since February at a square near the university in the capital Sanaa to end the rule of President Ali Abdullah Saleh say they are determined to stay put.
"This will be the month of change, especially since Ali Abdullah Saleh is not in Yemen," said Walid al-Omari, an activist from the country's "Youth Revolution" group.
Saleh is convalescing in Saudi Arabia after being wounded in a June 3 blast at his palace compound. He has refused to relinquish power and on Sunday called anew for a dialogue with the opposition.
Ramadan is the ninth month of the lunar Islamic calendar when Archangel Gabriel revealed the Koran -- Islam's holy book - to the Prophet Mohammed in 610 AD.
Throughout the month devout Muslims must abstain from food, drink and sex from dawn until sunset when they break the fast with the "iftar" meal. The last meal before dawn is known as suhur.
The fast is one of the five pillars of Islam, along with the annual pilgrimage to Mecca which able Muslims should do once in a lifetime, alms-giving, the profession of the faith, and the five daily prayers.
All post-puberty Muslim believers are expected to fast during Ramadan. Women who are pregnant or breast-feeding, the sick and travellers are exempted but they must fast again as soon as they are able.
The exact dates of the start and the end of Ramadan depend on the sighting of the new moon as many Muslim countries reject using astronomical calculation for the Muslim lunar calendar.
For most Muslim nations it started this year on Monday. The holy month ends with several days of feasting and gift-giving on Islam's biggest festival, Eid al-Fitr.