Violence in northwest Syria has displaced more than 30,000 people this month alone, the UN said Monday (September 10th), warning that a looming assault could create the century's "worst humanitarian catastrophe", AFP reported.

Idlib province and adjacent rural areas form the largest piece of territory still held by Syria's opposition fighters.

President Bashar al-Assad has now set his sights on Idlib, and his forces have stepped up bombardment of the densely populated province since the beginning of the month.

That has prompted an estimated 30,452 people to be displaced within Idlib and parts of adjacent Hama province between September 1st and 9th, the UN's humanitarian co-ordination agency (OCHA) said.

"We are deeply concerned about this recent escalation of violence, which has resulted in the displacement of over 30,000 in the area. That is something we are monitoring very closely," OCHA spokesman David Swanson said.

Many made a dash for Syria's northern border with Turkey, with just under half seeking refuge in displacement camps and others living with local families or renting apartments.

An AFP correspondent in Idlib has seen dozens of displaced families head towards the frontier in recent days to escape bombing elsewhere.

On Monday, on the main highway running across the province, men on motorbikes headed north with their children on foot, herding dozens of sheep.

UN humanitarian chief Mark Lowcock made an urgent appeal Monday, saying that "there needs to be ways of dealing with this problem that do not turn the next few months in Idlib into the worst humanitarian catastrophe with the biggest loss of life in the 21st century".