BEIRUT (AP) — A battle between Syrian government forces and rebels for the northwestern Idlib province could affect the lives of more than 1 million children, many of whom live in refugee camps, the U.N.’s children’s agency warned on Friday.

Food, water, and medicine are already in short supply in the largely rural province, which is now home to over 1 million Syrians displaced from their homes by government offensives in other parts of the country, said UNICEF.

The agency said a battle for Idlib, the last major bastion for Syria’s political and military opposition, would exacerbate an already dire humanitarian situation there and potentially displace 350,000 children.

Syria’s government dropped leaflets across the province on Thursday, urging residents to reconcile with its rule. Officials have warned that government forces will take back the province by force if necessary.

There are 2.9 million people living in Idlib and surrounding opposition-held areas, according to U.N. estimates.

“War cannot be allowed to go to Idlib,” said Jan Egeland, a top U.N. humanitarian adviser on Syria.

The U.N. has appealed on Turkey to open its border to refugees, should the Syrian government decide to attack the province, Egeland said.

Turkey, which has established itself as a sponsor of rebels in northern Syria, already hosts some 3.5 million Syrian refugees — the most of any nation. It has also established 12 monitoring posts in Idlib and deployed 1,000 troops in the province. Locals hope their presence will deter the Syrian government from attacking.

Syria’s civil war has killed at least 400,000 people, according to monitors. More than 11 million — or half of Syria’s pre-war population — have been displaced from their homes, according to the U.N., including some 5.6 million who have been made refugees abroad.