BEIRUT, (Reuters) – Syrian troops killed at least one person as they swept into a coastal city Saturday, activists said, in a crackdown on protests against President Bashar al-Assad which drew criticism from an international Muslim group.

The 57-member Organization of Islamic Cooperation, adding its voice to growing Arab pressure on Assad, called for the immediate halt of the military campaign against protesters which activists say has killed 1,700 civilians in five months.

Saturday’s killing in the Mediterranean city of Latakia came a day after security forces shot dead 20 people during nationwide marches in which demonstrators called for Assad’s overthrow and vowed defiantly they would “kneel only to God.”

The British-based Syrian Observatory for Human Rights said one person was killed and 15 wounded in heavy gunfire after around 20 military vehicles entered the southern Ramle district of Latakia, where 10,000 people had demonstrated Friday.

Soldiers backed by loyalist militia known as shabbiha also deployed in the city’s Sulaiba district, the group’s head Rami Abdel Rahman said. “They are arresting dozens of people,” he said, adding that many people were fleeing the assault.

He also reported that soldiers and shabbiha raided Jousiyah village near the Lebanon border, carrying out arrests.

Syrian authorities have barred most independent media, making it difficult to verify events on the ground in the unrest, one of a series of popular revolts against autocratic Arab leaders this year.

MUSLIM BODY CALLS FOR END TO BLOODSHED

Since the start of the Muslim holy month of Ramadan in early August, Assad has stepped up the military campaign, launching army assaults on the central city of Hama and the city of Deir al-Zor in the eastern Sunni Muslim tribal heartland. Assad’s family, which has ruled Syria for 41 years, is from the minority Alawite sect.

After a wave of Arab criticism of Damascus last week, the Saudi Arabia-based Organization of Islamic Cooperation (OIC) accused Syria Saturday of using “excessive armed force” and called on Damascus to stop the bloodshed.

OIC Secretary-General Ekmeleddin Ihsanoglu urged Assad “to exercise utmost restraint through the immediate halt to the use of force to suppress popular demonstrations.”

Authorities say 500 soldiers and police have been killed by armed groups who they blame for the violence. The state news agency SANA said three members of the security forces were killed during Friday’s protests.

U.S. Secretary of State Hillary Clinton said Friday Syria would be better off without Assad and called on nations that buy oil or sell arms to Syria to cut those ties.

“We urge those countries still buying Syrian oil or gas, those countries still sending Assad weapons, those countries whose political and economic support give him comfort in his brutality, to get on the right side of history,” she said.

Syria’s oil industry, with which the Assad family has close links, generates most of the state’s hardcurrency from crude output of 380,000 barrels per day.

While Syria exports crude oil, its refinery capacity is not sufficient to meet domestic demand for fuel. Trading sources said Swiss oil traders Vitol and Trafigura agreed to supply state firm Sytrol with 60,000 tonnes of gasoline this week.

The global campaign group Avaaz urged European nations on Friday to impose immediate restrictions on purchases of Syrian oil to “dry up” funding of Assad’s forces. It said more than 150,000 Avaaz members had signed a petition to that effect.

Wednesday Washington imposed sanctions on Syria’s largest bank and its biggest mobile telephone company, controlled by Assad’s cousin Rami Makhlouf. The next day, U.S. Ambassador to Damascus Robert Ford said more sanctions would follow if the Syrian authorities did not halt the violence.