UNITED NATIONS -- UN humanitarians on Monday described the situation in Syria as chaotic and fluid, with more than 16 million people in the country requiring assistance.

The UN Office for the Coordination of Humanitarian Affairs (OCHA) said 1 million people were displaced from their homes in the west and northwest alone from Nov 28 to Dec 8. "There is an urgent need for more shelter, food, and sanitation facilities."

The office said the recently displaced were primarily women and children from Aleppo, Hama, Homs and Idlib governorates. The situation is very fluid, with reports of more people returning in the last couple of days. Transportation routes were disrupted, limiting the movement of people, goods and humanitarian aid.

Some looting of civilian properties and factories, as well as warehouses holding humanitarian supplies, has been reported, according to OCHA.

"Despite the challenges and the volatile situation, we and our partners continue to provide emergency aid," the office said.

The office said that in northwest Syria, all humanitarian organizations in Idlib and northern Aleppo resumed regular operations and the three border crossings from Türkiye used to deliver aid into Syria remained open.

"In the northeast, we are providing supplies for those who recently fled Aleppo," OCHA said. "In Aleppo, we are providing basic assistance including food, health and nutrition services, and support for access to clean water."

However, the office said that health facilities are overwhelmed, with major hospitals operating at limited capacity due to shortages of staff, medicine and supplies.

"Our health partners continue to provide critical services in impacted areas, including providing trauma care kits." OCHA said. "They have also deployed medical units in reception centers and schools across Raqqa, Tabqa and Al-Hasakeh."

The UN Children's Fund (UNICEF) and the UN Population Fund (UNFPA) deployed mobile teams and established fixed clinics in Homs. In northwest Syria, all 24 health facilities that had suspended operations recently resumed services, although others remain non-functional.

"Syria is at a crossroads between peace and war, stability and lawlessness, reconstruction or further ruin," UN High Commissioner for Refugees (UNHCR) Filippo Grandi said in a statement.

"There is a remarkable opportunity for Syria to move toward peace and for its people to begin returning home. But with the situation still uncertain, millions of refugees are carefully assessing how safe it is to do so. Some are eager, while others are hesitant," he said.

"UNHCR's advice is to remain focused on the issue of returns," Grandi said. "Patience and vigilance will be necessary, hoping that developments on the ground will evolve in a positive manner, allowing voluntary, safe and sustainable returns to finally occur -- with refugees able to make informed decisions."

Grandi said that as the situation evolves, UNHCR will monitor developments, engage with refugee communities and support states in any organized voluntary returns.

Some voices have been heard in nations hosting refugees on forcing refugees to return to their homes in Syria as Bashar al-Assad's government has collapsed following a sweeping offensive by militant groups.

Stephane Dujarric, the spokesman for UN Secretary-General Antonio Guterres, said the world body calls on donors to ensure that UNHCR and its partners have the resources to respond swiftly and effectively, including in neighboring countries still hosting millions of refugees.

"These countries need international support to sustain their exceptional solidarity and generosity," Dujarric said. "Resources need to be provided as flexibly as possible to allow for assistance to be provided where it is most needed."