* 100,000 children out of reach in rebel-held Raqqa province
* Some 2.15 million Syrian children vaccinated against polio
* Red Cross says food, medicines run short in besieged areas
By Stephanie Nebehay
GENEVA, Jan 13 (Reuters) - Heavy fighting has prevented health workers from getting polio vaccine to an estimated 100,000 Syrian children in the northeastern province of Raqqa, United Nations aid agencies said on Monday, appealing for access.
The crippling infectious disease was confirmed in 15 children in Syria in October, the first outbreak there since 1999. A nationwide campaign was launched in November to vaccinate some 2 million Syrian children under five each month until May.
The World Health Organization (WHO) and the U.N. Children's Fund (UNICEF) condemned the halt of the immunisation campaign in Raqqa province due to intense fighting in Syria's civil war.
Polio poses a "serious risk" in Syria and the region and all children have the right to be protected from the disease, which can paralyse a child within hours, they said in a statement.
"We haven't reached Raqqa town in this second round of immunisation. There are approximately 100,000 children out of reach in the town and its outskirts," Elizabeth Hoff, WHO representative in Syria, told Reuters from Damascus.
Raqqa is the only provincial capital under rebel control and WHO has no direct contact with Islamist groups there, she said. The al Qaeda-linked Islamist State of Iraq and the Levant executed dozens of rival Islamists over the last two days as the group recaptured most territory it had lost in Raqqa, activists said on Sunday.
Some 2.15 million children across Syria were reached last week with polio vaccine during this second round of mass immunisation, including some in Raqqa province, Hoff said.
"The information campaign has been very strong, parents are bringing their children. The uptake is very good," Hoff said.
"At least we haven't seen any new cases since October," she added. That month saw 13 cases in Deir al-Zor, in the east, and single cases in Aleppo, in the north, and Douma (Rural Damascus).
Syria's government and some rebels may be willing to permit humanitarian aid to flow, enforce local ceasefires and take other confidence-building measures in the nearly three-year-old conflict, U.S. Secretary of State John Kerry said on Monday.
Kerry held talks in Paris with Russian Foreign Minister Sergei Lavrov and U.N. mediator Lakhdar Brahimi, who has convened peace talks in Switzerland next week in an attempt to end the conflict that has killed more than 100,000 people and forced millions to flee.
Peter Maurer, president of the International Committee of the Red Cross (ICRC), appealed for greater access for aid workers at the end of a three-day visit to Syria.
"Health supplies, food and other basic necessities are running dangerously short, especially in besieged areas, where the situation is critical," Maurer said in a statement.