GENEVA — United Nations officials confirmed an outbreak of polio among children in Syria on Tuesday, lending urgency to plans for vaccination campaigns there and in nearby countries to try to halt the spread of the disease.

Tests confirmed polio in 10 out of 22 children in Deir al-Zour Province in northeastern Syria who became ill this month, said Oliver Rosenbauer, a spokesman for the World Health Organization. Results of tests on the other 12 children are expected soon, he added.

“With population movements, it can travel to other areas,” Mr. Rosenbauer said, “so the risk is high of spread across the region.”

United Nations officials said last week that they were beginning a campaign to immunize 2.4 million children in Syria against polio and other diseases. With thousands of refugees fleeing daily from Syria’s civil war to neighboring countries, the officials are also intensifying immunization efforts in six countries: Lebanon, Jordan, Iraq and Turkey, which have taken in more than two million Syrian refugees, as well as Egypt and Israel.