Saudi Arabia issued a terse warning to Syrian President Bashar al-Assad on Monday to stop waging a violent campaign against protesters, or face defeat.
The warning came after a bloody tank attack in Syria's Sunni Muslim heartland. One day earlier, dozens of civilians were killed in clashes with the military.
Dissidents have been fighting for more political freedom and demanding al-Assad's departure.
Saudi Arabia's King Abdullah added his voice to the protests on Monday, demanding an end to the bloodshed and recalling the Saudi ambassador from Damascus.
"What is happening in Syria is not acceptable for Saudi Arabia," Abdullah said in a written statement read out on Al Arabiya satellite television.
"Syria should think wisely before it's too late and issue and enact reforms that are not merely promises but actual reforms, he said.
"Either it chooses wisdom on its own or it will be pulled down into the depths of turmoil and loss."
Kuwait and Bahrain followed the lead of the powerful Arab nation, recalling their own ambassadors just hours later.
All three countries had remained silent about the ongoing tensions, which began five months ago, until Monday.
Earlier Monday the eastern city of Deir el-Zour came under artillery fire again Monday morning, a day after dozens of civilians were killed in clashes with the military.
The Local Coordinating Committees, which help organize the protests and track the uprising, said machine fire and artillery blasts were heard early Monday in Deir el-Zour.
"Forces entered the city from its eastern side and they are preventing the residents from entering or leaving the city," the LCC said in a statement.
One activist told the Associated Press that people in Deir el-Zour were too terrified to take the wounded to government hospitals, instead treating them at home or in makeshift hospitals. He spoke on condition of anonymity for fear of reprisals.
Syrian troops also stormed Maaret al-Numan in the northern province of Idlib at dawn, activists told AP.
After sunset Sunday, thousands of people poured into the streets in towns all over Syria, including the capital Damascus, Dael in the south, Homs, Latakia on the Mediterranean coast, and the northern city of Aleppo, according to the LCC.
There were reports of shootings but no immediate word on casualties.
More than 300 people have died in Syria in the past week, the bloodiest week in the five-month uprising against President Bashar Assad's authoritarian rule. In all, more than 1,700 have died since March, say activists and human rights groups.
Assad's regime disputes the toll. It has blamed armed gangs for the violence, while offering reform measures that have failed to satisfy the protesters who want sweeping changes. The protesters say they want an end to the Assad family's 40-year rule.
Syrian-Canadian activist Mohamed Mahmoud, says people are simply fighting for the human rights of freedom, democracy and dignity.
"There are not enough words to tell the regime that its politics of killing more people who are asking for basic human rights is just unacceptable," Mahmoud told CTV's Canada AM Monday morning.
Syria is promising it will hold free and transparent elections "that will give birth to a parliament representing the aspirations of the Syrian people,'' the Foreign Minister, Walid Muallem, told a meeting of ambassadors in Damascus over the weekend.
But Mahmoud says he doesn't believe that.
"This is another lie, actually. It's what the regime has been doing since the uprising started in Syria: just telling people lie after lie. And it believes its own lies now," he said.
Mahmoud says what has been promised isn't presidential elections; they're elections for legislators - and they were scheduled before the uprising started.
"And believe me: they will be fabricated, these elections; they won't be free," Mahmoud said.
The international community has sharply condemned Syria's crackdown on protesters, imposing sanctions and demanding an immediate end to the attacks.
But in a sign of growing outrage, Syria's Arab neighbours have now joined the criticism, voicing their concerns over the crackdown.
Jordan's top diplomat expressed concern over the bloodshed but stopped short of condemning its neighbour.
Foreign Minister Nasser Judeh was quoted by Jordan's official Petra News Agency describing the escalation in violence as "disturbing." He urged Damascus to follow through on promised reforms.
The 22-member Arab League, which, until now, has remained silent about the uprising, said Sunday it is "alarmed" by the situation in Syria and called for the immediate end to the violence.
With reports from The Associated Press
