Bashar Assad's militia, backed by Russian air power, have been waging an offensive in the Idlib region, the major remaining rebel-held territory in Syria's war.
“That counterterrorism can’t put three million civilians at risk. They have the right of protection under the International human rights and humanitarian law. The actions of killing and displacing them must stop now. The situation in Idlib needs a predominately political solution,” Special Envoy of Secretary-General for Syria Geir Pederson said.
Kuwait, Germany and Belgium circulated a draft resolution, seen by Reuters, to the 15-member U.N. Security Council late on Wednesday that would express "outrage at the unacceptable levels of violence escalating in and around Idlib." It was not immediately clear when they aimed to put it to a vote.
A resolution needs nine votes in favor and no vetoes by Russia, China, the United States, France or Britain to pass.
"Three million people - two-thirds of them women and children - are counting on your support to make this violence stop," UN aid chief Mark Lowcock told the Security Council on Thursday.
UN Secretary-General Antonio Guterres announced earlier this month that the world body would investigate attacks on UN-supported facilities and other humanitarian sites in northwest Syria.