June 26 (UPI) -- Pro-Syrian government forces are escalating their attacks against rebel-held towns in Daraa as thousands flee the area.
Leaflets dropped Monday warned residents the army was coming and urged civilians to "kick out the terrorists" and to "cooperate" with the government forces.
Tuesday, clashes broke out between forces loyal to Syrian President Bashar al-Assad and rebel fighters.
"At least 200 air strikes and 150 barrel bombs targeted Basr al-Harir this morning as government forces moved in on the village," Jihad Hamza, a pro-opposition activist in Daraa, told Al Jazeera.
"Rebel fighters are organizing themselves to push back the assault."
Thousands of people have fled the area as the fighting escalates between the two sides. The United Nations estimates at least 45,000 people have fled towards Jordan.
U.N. Secretary-General António Guterres called for an "immediate end" to the fighting.
"The attacks have resulted in the displacement of thousands of civilians, the majority of whom are moving towards the Jordanian border," Guterres said in a statement. "The Secretary-General is also concerned at the significant risks these offensives pose to regional security."
Ayman Safadi, Jordan's foreign minister, tweeted Sunday his country couldn't accept more refugees.
"We urge all parties to uphold ceasefire south Syria to avert new catastrophe," Safadi tweeted, adding the solution to the fighting was "political" in nature.
Amnesty International criticzed the decision to not accept refugees and asked Jordan not to "abandon them."
"Jordan has a duty to protect refugees from Syria fleeing conflict and persecution, and to allow them to enter the country," Amnesty International said. "Closing the border to people in need of protection violates Jordan's international obligations."