The Syrian government, supported by Russian air power, has for months waged a large-scale offensive against rebels in Idlib, forcing thousands of people to flee.
Idlib is a largely opposition-held province near the Turkish border.
"Upwards of 80,000 people have reportedly been displaced from southern Idlib since the start of November, many of them multiple times, with thousands more reportedly on the move," David Swanson, regional spokesman for the United Nations Office for the Coordination of Humanitarian Affairs (OCHA), told dpa.
"With the front line moving rapidly, civilians continue to flee from towns and villages in southern Idlib, fearing that the hostilities may affect their homes next," he added.
He added that the UN and its partners are working tirelessly around the clock to address the needs of those affected, "but ongoing issues of insecurity and access are proving particularly challenging."
"These newly displaced add to the over 400,000 women, children and men that were displaced as a result of hostilities since the end of April, many of them multiple times, and an already dire humanitarian situation on the ground," he said.
The White Helmet rescue organization said 12 people, including six children and three women, were killed Tuesday in Idlib. Ten of the victims lost their lives after a Russian airstrike targeted their camp, the group tweeted.
Nine other areas were targeted by 15 airstrikes and over 56 artillery shells, it said.
The Britain-based Syrian Observatory for Human Rights on Tuesday said the airstrikes targeted the village of Joubas, on the outskirts of the town of Saraqeb, east of the province of Idlib.
The government's offensive against rebels in the provinces of Hama and Idlib began on April 30. The Syrian forces have since regained territory from the rebels in the two provinces.
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