UNITED NATIONS • Hundreds of thousands of people fleeing a Russian-backed Syrian offensive are being squeezed into ever smaller areas near Turkey’s border “under horrendous conditions” in freezing temperatures that are killing babies and young children, the U.N. humanitarian chief said Wednesday.

Mark Lowcock told the U.N. Security Council that “the unfolding humanitarian catastrophe” in northwest Idlib province, which is the last major rebel stronghold, has “overwhelmed” efforts to provide aid.

He said nearly 900,000 people have been displaced since Dec. 1 when the government offensive began, more than 500,000 of them children.

“Many are on foot or on the backs of trucks in below-freezing temperatures, in the rain and snow,” Lowcock said.

“They are moving into increasingly crowded areas they think will be safer. But in Idlib, nowhere is safe.”