Thousands of Syrian refugees were massed on Monday along the border, hoping to cross into Turkey to escape a crackdown by elite army troops who retook control of one rebellious town and threatened to widen their assault on anti-government activists.
State media described heavy fighting as troops led by President Bashar Assad's brother regained control of Jisr al-Shughour Sunday, sending in tanks and helicopter gunships after shelling the town. But residents were still terrified; more than 6,000 Syrians have sought sanctuary in Turkey, nearly all of them in the past few days from Idlib province.
The influx of refugees into neighboring Turkey is straining ties between the two allies. Prime Minister Recep Tayyip Erdogan, who won a landslide victory in Sunday's general elections, has said he would speak to Assad soon.
Syria's official media reported the discovery of a mass grave in Jisr al-Shughour, a town that has been the center of the protests and mutiny. Government officials say 120 security personnel were killed in the town last week by gunmen in stolen army uniforms.
Reporters, who have been banned from the area for weeks, were allowed in for the first time on Monday to witness the mass grave, but it was not clear who was responsible for the killing — the opposition or the Syrian military.
In a refugee camp inside Turkey, many residents of Jisr al-Shughour have given consistent accounts of mutinous security personnel who were murdered by officers after refusing orders to fire on civilians.
If true, the mutiny would pose one of the most serious threats to the Assad regime since protests against his rule began in mid-March. Assad has made some concessions, but thousands of demonstrators say they will not stop until he leaves power.
The Local Coordination Committees, a group that documents the protests, said government snipers have killed at least 10 people in the past two days in Ariha, a village near Jisr al-Shughour.
More than 1,400 Syrians have died and some 10,000 have been detained in the government crackdown since mid-March, activists say.
"Assad's men are killing anyone within the military, police or others who don't obey their orders blindly," a man who gave his name as Abu Ali told The Associated Press. "They are killing those who want freedom."
On Monday, Syria imposed a travel ban on one of the president's cousins, a move that appeared to be an attempt to show Assad is serious about investigating the bloodshed.
The state-run SANA news agency says the ban was imposed on Brig. Gen. Atef Najib, who ran the security department in the southern province of Daraa. The uprising erupted there in mid-March after the arrest of 15 teenagers who scrawled anti-government graffiti.
Judge Mohammed Deeb al-Muqatran of the Special Judicial Committee said the travel ban is precautionary in order for Najib to be available for questioning.
Al-Muqatran was quoted as saying Monday that "no one has immunity, whoever he is."
In apparent anticipation of more refugees, workers of the Turkish Red Crescent, the equivalent of the Red Cross, began building a fourth tent camp Monday near the border.
Turkish authorities have blocked the media from entering the camps. Turkey appears to be trying to limit publicity directed at the crisis.
Erdogan's rhetoric against Syria has grown steadily harsher. He now accuses Damascus of committing "atrocities" and "savage repression." Like the West, he has stopped short of calling on Assad to step down.
Mustafa Akyol, a writer and analyst, says Ankara was forced to act as the flow of goods across the Syrian border was dwarfed by the flow of refugees.
"The Arab Spring brought a new angle that Turkey had not foreseen before: What do you do when a country that you have good relations with starts to kill its own people?" he said. "Turkey fell into this dichotomy between 'realpolitik' and 'moralpolitik,' as Americans always do."
Turkey and Syria once nearly went to war, but the two countries have cultivated warmer relations in recent years, lifting travel visa requirements for their citizens and promoting business ties.
Analyst Hugh Pope with the International Crisis Group says Erdogan, newly empowered with a solid mandate at home, will probably continue to reshape the increasingly tense relationship with the Assad regime.
"They're becoming very, very frustrated, and they're not making any secret of it anymore," Pope said. "I think like everybody they're leaving the door open a crack, hoping that — a miracle — that Bashar al-Assad will see that the security option is actually bringing the house down around his ears. But I don't think that the regime in Damascus is listening to anybody right now."
Pope says Syria has always known that its ties with Turkey were a double-edged sword, bringing in not only goods and services but a greater appreciation among the Syrian public for Turkish freedoms. He says it can hardly have gone unnoticed in Damascus that Syrian demonstrators have been seen carrying Erdogan's picture. Still, Pope adds, those relations could also provide leverage for an effort to end the violence in the right circumstances.
"Because one thing that makes Turkey different to the U.S. approach to the Mideast is that Turkey has a very broad relationship with Syria," he said. "At the end of the day, Turkey — the prime minister's in a much stronger position, and I think it will be the guys in Damascus who will be watching very carefully what he does."
NPR's Peter Kenyon in Istanbul, Turkey, and Deborah Amos in Beirut, Lebanon, contributed to this report, which includes material from The Associated Press