Albert Aji?and Dusan Stojanovic

DAMASCUS, Syria: The U.N. confirmed an outbreak of polio in Syria for the first time in over a decade on Tuesday, warning the disease threatens to spread among an estimated half-million children who have never been immunized because of the civil war.

The grim finding added another layer of misery to a brutal conflict that has already killed more than 100,000 people and uprooted millions.

The aid group Save the Children urged a “vaccination cease-fire” to try to prevent an epidemic of the highly contagious disease.

Meanwhile, hopes for a negotiated settlement to the three-year conflict appeared ever more distant as Syria’s President Bashar Assad sacked a deputy prime minister for meeting with Western officials to discuss the possibility of holding a peace conference — the latest blow to diplomatic efforts to bring the country’s warring parties to the negotiating table.

At least 10 cases of polio among babies and toddlers were confirmed in northeastern Syria, the World Health Organization said — the first outbreak of the crippling disease in 14 years. Nearly all Syrian children were vaccinated against polio before the civil war began.

WHO spokesman Oliver Rosenbauer said the U.N. agency was awaiting lab results on another 12 suspected cases, mostly children under 2.

“This is a communicable disease. With population movements it can travel to other areas,” Rosenbauer said. “So the risk is high of spread across the region.”

Regionally, neighboring Lebanon and Jordan are likely to be at particular risk because the two countries have absorbed the bulk of Syrian refugees fleeing war-torn areas, where it’s more likely that children haven’t been vaccinated.

The polio virus usually infects children in unsanitary conditions through consuming food or drink contaminated with feces. It attacks the nerves and can kill or paralyze, spreading widely and unnoticed before it starts crippling children.

On Tuesday, rebels and Syrian forces observed a temporary cease-fire to allow nearly 2,000 residents to flee the besieged Damascus suburb of Moadamiyeh.

Men, women and children crossed over a no man’s land, while some elderly and ill residents were carried by Red Crescent workers. Many young men were among those fleeing, and government officials said they included surrendering rebels, who were taken on separate buses.

In a setback to efforts to bring a quick end to the conflict, Syrian Deputy Prime Minister Qadri Jamil was fired Tuesday after meeting in Geneva with the U.S. ambassador to Syria, Robert Ford.