Syrian soldiers were blocking access to the border   Syrian troops backed by tanks entered a border zone sending hundreds of people fleeing into Turkey as US Secretary of State Hillary Clinton warned of a possible escalation of the conflict. Clinton said the troop build-up was \"worrisome\" as it could increase the chances of a border clash and spell fresh misery for refugees fleeing a crackdown following pro-democracy protests, which hit the 100-day mark on Thursday.
Syrian troops backed by tanks stormed the border village of Khirbet al-Joz, where many of the displaced had massed, an activist at the scene told AFP.
A resident of Guvecci in Turkey said he saw soldiers crossing a hill on the Syrian side less than a kilometre from the border after dawn.
About 600 people broke through barbed wire marking the frontier to seek haven in Turkey, advancing on a road a few kilometres (miles) from the village of Guvecci.
Several hundred more people were seen down the road and the authorities brought in minibuses to ferry the refugees to tent cities set up by the Turkish Red Crescent in Hatay border province.
A Turkish smuggler with relatives on the Syrian side told AFP tanks were on standby at Khirbet al-Joz, but plainclothes police were descending on farms outside the village, 500 metres (yards) from the frontier.
And a Syrian imam who arrived in Guvecci on Thursday told AFP that Syrian soldiers were blocking access to the border.
\"The army took control of villages and are blocking roads,\" the cleric who identified himself as Rami said, adding that he fled with the help of a people smuggler after hearing gunfire.
\"We are very concerned by the reports that the Syrian military has surrounded and targeted the village of Khirbet al-Joz, which is located roughly 500 metres from the Turkish border,\" Clinton told reporters in Washington.
\"If true, that aggressive action will only exacerbate the already unstable refugee situation in Syria,\" she said.
\"And it just is very clear to us that unless the Syrian forces immediately end their attacks and their provocations that are not only now affecting their own citizens but endangering the potential border clashes, then we\'re going to see an escalation of conflict in the area,\" Clinton said, calling it a \"very worrisome development.\"
The Local Coordinating Committees organising the protests meanwhile vowed to keep the heat on President Bashar al-Asad\'s regime and pursue the \"peaceful revolution until we have a free and democratic Syria.\"
The European Union also ramped up pressure, adopting new sanctions that added 11 more individuals and businesses to a list of Syrians already targeted, diplomats said.
The head of the Turkish Red Crescent Tekin Kucukali spoke of a \"surge of activity at the border.\"
\"There were over 600 entries today,\" he said, adding that more than 11,000 Syrians had taken refuge in Turkey.
Turkish Foreign Minister Ahmet Davutoglu discussed the border situation separately over the phone with his Syrian counterpart Walid Muallem and EU foreign policy chief Catherine Ashton, Anatolia news agency reported.
The Turkish foreign ministry also summoned Syria\'s ambassador for talks on the situation, it said.
Thousands of Syrians have flocked to the border but many have hesitated to enter Turkey, wary of leaving their property behind, and live in the open air or in makeshift shelters, surviving on scarce food and water.
Syria\'s official SANA news agency reported on Thursday that more than 700 refugees had returned home to the restive northern border town of Jisr al-Shughur.
Meanwhile the London-based Syrian Observatory for Human Rights said security forces arrested more than 120 people late on Wednesday and early on Thursday in and around Tall Rifaat village near the border.
More than 1,300 civilians have been killed and 10,000 people arrested since pro-democracy protests erupted on March 15, Syrian human rights groups say.
Activists said a call by the Facebook group Syrian Revolution 2011 for a general strike to mourn those killed in the crackdown was partly observed.
The group also called on Syrians to stage rallies on Friday, the weekly Muslim day of rest and prayer that has become a springboard for demonstrations, to signify the regime has lost its legitimacy.
\"Bashar is no longer my president and his government no longer represents me,\" is the theme for Friday\'s rallies.
Oscar-winning film director Woody Allen on Thursday joined two Nobel prize winners in a petition demanding that the UN Security Council condemn the Syrian government crackdown on opposition protests, organisers said.
Allen, Nobel literature prize winners Wole Soyinka of Nigeria and Orhan Pamuk of Turkey and leading writers such as Salman Rushdie, Umberto Eco and Bernard-Henri Levy are all calling for a UN resolution.