Secretary of State Hillary Clinton on June 23 said the reported Syrian troops movements were "very worrisome".

She said it could increase the risk of a border clash with Turkey and worsen the plight of refugees.

Syrian tanks and snipers reportedly entered the village of Khirbet al-Jouz, forcing resident to flee to Turkey.

More than 1,300 people are said to have been killed since a crackdown on anti-government protests began in March.

Thousands more protesters have been detained, opposition activists say.

Several Syrian cities - including Homs and Hama - have declared a general strike after deadly clashes with security forces and supporters of President Bashar al-Assad earlier this week.