AMMAN (Reuters) – Syrians began the Muslim Ramadan fast in somber mood on Monday after troops stormed Hama, scene of a 1982 massacre, in one of the bloodiest days of a five-month-old uprising against President Bashar al-Assad.

Rights activists said 80 civilians were killed in Sunday’s tank-backed assault on the central Syrian city where Assad’s father crushed an armed Muslim Brotherhood revolt 29 years ago by razing neighborhoods and killing many thousands of people.

Security forces, dominated by Assad’s minority Alawite sect, had besieged the Sunni Muslim city of 700,000 for nearly a month before Sunday’s crackdown on the eve of Ramadan, a holy month when Muslims fast in daylight hours.

Many people flock to mosque prayers at night, occasions which protesters may use to launch more frequent protests.

In a letter to the military, Assad reiterated that Syria was facing a foreign conspiracy to sow sectarian strife designed to “tear Syria into small statelets that compete to satisfy those who worked to slice them up.”

“All of Syria’s honorable people are sure that we will emerge stronger from the crisis,” Assad said.

“They wanted to wreak sectarian strife that destroys everything. We managed to prevent sectarian strife and examine ourselves to find out the errors and treat them.”

The 1982 Hama massacre instilled such fear that few Syrians were ready to challenge Assad family rule openly until this year, when many were inspired by the largely peaceful popular uprisings that toppled Arab autocrats in Egypt and Tunisia.

The Muslim Brotherhood accused the Alawite elite of waging sectarian warfare on Sunnis by attacking Hama.

“SECTARIAN CLEANSING”

“Syria is witnessing a war of sectarian cleansing. The regime has linked its open annihilation with the crescent of Ramadan. It is a war on the identity and beliefs of the Syrian nation … on Arab Muslim Syria,” it said in a statement.

The Syrian leadership blames “armed terrorist groups” for most killings during the revolt, saying that more than 500 soldiers and security personnel have been killed.

The Syrian state news agency said the military entered Hama to purge armed groups that were terrorizing citizens, an account dismissed as “nonsense” by a U.S. diplomat in Damascus.

The agency said eight police personnel were killed while “confronting armed terrorist groups” in Hama.

Residents said tanks began pounding neighborhoods of the city after attacking from several directions in a dawn assault.

“The authorities think that somehow they can prolong their existence by engaging in full armed warfare on their own citizens,” U.S. Press Attache J.J. Harder told Reuters.

Footage posted on social media showed large parts of the city covered in smoke, and panic-stricken groups around dead or wounded people in the streets as gunfire rang out. Reuters could not independently verify the content of the videos.

Other footage purporting to be from the city of Homs showed crowds chanting: “Hama, we are with you until death, Deir al-Zor, we are with you until death.”

Residents said at least 11 civilians had been killed in a weekend crackdown in the eastern province of Deir al-Zor.

In Deir al-Zor city, gunfire echoed through empty streets after pre-dawn prayers. “Most people are in their houses, but we can hear shooting in the streets,” a resident said.

U.S. President Barack Obama said he was appalled by the Syrian government’s “horrifying” violence against its people in Hama and promised to work with others to isolate Assad.

“Syria will be a better place when a democratic transition goes forward,” Obama said in a statement.

Several European countries condemned the Hama assault. Italy and Germany called for a U.N. Security Council meeting, but Britain ruled out any foreign military intervention.

The council was expected to hold closed-door consultations on Monday, a spokesman for Germany’s U.N. mission said.

NO FOREIGN INTERVENTION

“We do want to see additional sanctions,” British Foreign Secretary William Hague told the BBC. “We want to see stronger international pressure all round. Of course, to be effective, that can’t just be pressure from Western nations, that includes from Arab nations, it includes from Turkey.”

Seeking military action against Syria, even with U.N. authority, was “not a remote possibility,” he said.

Russia and China have previously opposed any condemnation of Syria in the council, where they hold veto powers.

The European Union plans to extend sanctions on Monday by slapping asset freezes and travel bans on five more Syrians. EU sanctions already target Assad and at least two dozen officials, as well as Syrian firms linked to the military.

Turkey, one of Assad’s main allies until the uprising, felt “great disappointment and sadness” over Sunday’s death toll, Foreign Minister Ahmet Davutoglu said, blaming the use of tanks and heavy weapons for the high number of casualties.

“Such a start to Ramadan for Syrians is not acceptable. We condemn the attack,” Davutoglu said. “Our advice to Syrian officials has been the same all along: the promised reforms should be carried out right away.”

The Syrian human rights group Sawasiah put the civilian death toll in Hama at 80. Some reports gave higher figures.

Syrian authorities have expelled most independent journalists since the anti-Assad unrest began in March, making it difficult to verify reports of violence and casualties.

Assad has increasingly relied on security services and army units dominated by Alawites, at the heart of power since a 1963 Baath Party coup, to suppress protests in Sunni-majority Syria.