Several UN Security Council ambassadors expressed concern on Tuesday over the fate of civilians in Syria’s insurgent-held Idlib province, as government forces appear ready to re-take the region.

Following a Security Council meeting on the humanitarian crisis in Syria, Western countries warned that an attack by President Bashar al-Assad’s forces would have dire consequences, AFP reported.

“There are alarming signs of a pending military offensive in northwestern Syria,” said Carl Skau, Sweden’s ambassador to the Security Council. “Increased military escalation would have catastrophic consequences and can lead to a humanitarian disaster.”

The strategically important northwestern province of Idlib bordering Turkey is the last rebel holdout in Syria.

John Ging, a senior official with the UN Humanitarian Affairs office, said there has been a “serious deterioration of the humanitarian situation” in northwestern Syria in recent weeks.