The Syrian regime is gearing up for an expected offensive in Idlib province, which is home to nearly 3 million people and has a large al Qaida presence in addition to opposition and rebel groups.
The UN director of humanitarian operations warned a large-scale Syrian regime offensive in the last major opposition and rebel stronghold in northern Idlib province "has the potential to create a humanitarian emergency at a scale not yet seen" in the seven-year war.
John Ging called on members of the UN Security Council (UNSC) Tuesday "to do all they can to ensure that we avoid this."
The Syrian regime is gearing up for an expected offensive in Idlib province, which is home to nearly 3 million people and has a large al Qaida presence in addition to Syrian rebel and opposition groups. It borders Turkey, which fears an offensive may trigger a humanitarian and security catastrophe.
Ging said recent weeks have seen "a further serious deterioration of the humanitarian situation" with intense bombing and shelling reported in parts of Idlib as well as Aleppo, Hama and Latakia provinces resulting in civilian deaths and destruction of schools and hospitals.
He said humanitarian organizations are trying to sustain their current response and prepare for a possible further deterioration, "but a worst-case scenario in Idlib will overwhelm capacities and has the potential to create a humanitarian emergency at a scale not yet seen through this crisis."
More human displacement
UN Secretary-General Antonio Guterres also warned on Tuesday military escalation in northwestern Syria will lead to catastrophic consequences for civilians.
Guterres stressed in a report to the UNSC that an increase in military activity could trigger massive population movements in the country and leave residents of the region with severely limit access to humanitarian assistance and basic services.
"I reiterate that the perpetrators of serious violations of international humanitarian law must be held accountable. Such a step is central to achieving sustainable peace in the Syrian Arab Republic.
I also reiterate my call for the situation in the country to be referred to the International Criminal Court," he said.
Guterres called on all sides to avoid bloodshed and to "abide by the de-escalation agreement" and said that all parties in the conflict must adhere to international humanitarian law and protect civilians.
"There can be only one agenda for us all: to end the suffering of the Syrian people and to find a sustainable solution to the conflict in the country through an inclusive and Syrian-led political process that meets the legitimate aspirations of the Syrian people."
Warnings against chemical weapons
The United States, Britain and France have warned that they will respond "appropriately" to any chemical weapons attack in Idlib — a warning repeated to council members on Tuesday by all three countries.
Russia again accused Syrian rebels of preparing a chemical attack, which Moscow says the West will use to justify a strike against the regime forces. Russia also claims British special forces are helping the rebels, including by possibly supplying chlorine, allegations vehemently denied by Britain's UN Ambassador Karen Pierce who called them "baseless" and "outlandish."
"Having heard their case," Pierce told reporters after the council meeting, "it's very clear to us and our partners that this is an effort to distract from an imminent attack on Idlib."
Russia's UN Ambassador Vassily Nebenzia said Syrian regime forces have no chemical weapons and there is no need for them.
"People in their right minds will not use means that are useless from a military point of view in order to trigger reprisals by three major powers. But, of course, publicity about what is expected provocation could unleash the strikes," he said.
"Thank you for this warning of your response. We want to also warn you that we are absolutely aware of your unsavoury plans," Nebenzia said. "We strongly suggest that you refrain from them. Carrying out these plans will further deliver a strike against a peaceful resolution in Syria."
Pierce, the current Security Council president, was asked whether in closed consultations she saw any prospect that the 15 members would unite and respond to Ging's plea to avoid a humanitarian disaster in Idlib.
"The short answer is no, and that's very sad," she said.
"In closed consultations, the Russians backed off their original consultations a little bit. I'd like to think that that meant we might be able to get to a sensible outcome on Idlib in the council that helps protect civilians."
"But I'm afraid all the evidence so far is against us. We will still try," Pierce said.
US, Syrian security officials met in Damascus - sources
A US delegation including security and intelligence officials visited Damascus in June and met Syria's security chief, an official in the regional alliance backing the regime leader Bashar al Assad said on Tuesday.
Earlier on Tuesday, the pro-Hezbollah Lebanese newspaper al Akhbar reported the US delegation had held a four-hour meeting with Syrian security chief Ali Mamlouk near Damascus international airport.
Asked about the reports, two senior US intelligence officials, speaking on condition of anonymity, said there was an "ongoing dialogue with members of the Assad regime" about driving Daesh from Syria, Damascus' stockpile and use of chemical weapons, including chlorine, and the fate of journalist Austin Tice, who officials believe Damascus or its allies are holding.
Al Akhbar reported that the US officials had demanded the withdrawal of Iranian forces from southern Syria and data on "terrorist groups", including foreign fighters, and had also requested a role in the oil business in eastern Syria.
Mamlouk said Damascus would not cooperate with Washington on security issues until they had normalised ties and he also demanded a complete withdrawal of US forces from Syria, al-Akhbar reported.
The regional source told Reuters that most details in the al-Akhbar report were correct.
US officials have visited Damascus only rarely since 2011, when Washington started to back protests against Assad and later some of the armed rebels seeking to oust him.
Last year US President Donald Trump ordered a CIA-run military aid programme to the insurgents to be shut down.
In November, a senior regional official close to Damascus said a senior US official had met Mamlouk in the Syrian capital.