KILIS, Turkey—Aid workers rushed Sunday to provide shelter for more than 35,000 Syrians facing freezing temperatures and rain at the Turkish border as world leaders pressed Ankara to open its gates to a new surge of civilians seeking sanctuary from the fight for control of Syria's largest city.

The new influx has been sparked by Russian airstrikes in Aleppo helping the Syrian army and fighters dispatched by Iran in their renewed quest to retake the city from antigovernment rebel groups, just as United Nations-sponsored peace talks were suspended, damping hopes for an end to the fighting any time soon.

With fears growing that the city, once home to 2 million people, could soon be completely encircled by pro-regime forces, the fighting has triggered a new civilian exodus, with tens of thousands hoping to find sanctuary in Turkey, already home to 2.5 million refugees from the five-year-old Syrian war.

World leaders are pressing Turkey to open its border to the new influx but also want to ensure that a new flood of refugees doesn't head for Europe.

On Sunday, Deputy Prime Minister Numan Kurtulmuş warned that Turkey was straining to deal with the continued exodus from Syria.

"Turkey has reached the end of its capacity to absorb" refugees, Mr. Kurtulmus told CNN-Turk. But despite the strains, he said, Turkey would take in the Syrians if needed. "Either they will die beneath the bombings and Turkey will...watch the massacre like the rest of the world, or we will open our borders," he said.

Some Turkish leaders worry that accepting those who are fleeing Russian airstrikes will give Moscow more leverage to impose its will on the outcome of the war. "Right now Russia is responsible for the dirty game played over the refugees," said a Turkish government official near the border. "If Turkey takes the refugees now, it will have given the message to Russia that Turkey is accepting their plan in the region."

On Monday, German Chancellor Angela Merkel is expected to travel to Ankara to discuss the pressing refugee crisis with Prime Minister Ahmet Davutoglu and possible ways to address it.

The European Union is preparing to send more than $3 billion to help Turkey accommodate Syrian refugees—and to clamp down on the steady flow of smuggling boats delivering hundreds of new migrants to Greek islands each week.

European leaders warned this weekend that Western nations are likely to tighten their border controls if Turkey doesn't cut off the smuggler routes across the Aegean Sea within weeks.

Turkish officials have already stepped up their efforts to break up smuggling networks. But they said world leaders need to focus on the root problem: Ending the Syrian civil war that has killed more than 250,000 and forced millions from their homes.

In Monday's meetings, Turkish officials are expected to press their longstanding call for creation of a safe zone inside Syria that can serve as a new sanctuary for those displaced by the fighting.

"This will be Turkey's message to Merkel and European Union: We need to set up the safe zone for refugees," said a Turkish government official. "Without the safe zone, this crisis will only get deeper, and that would not be only Turkey's responsibility."

New calls for a safe zone are unlikely to find a receptive ear from European of American officials who aren't willing to commit the military resources needed to enforce a no-fly zone to protect civilians in any such area.

Now that Russian warplanes are flying daily missions over parts of northern Syria where Turkey wants to create the safe zone, the idea seems even more risky and remote.

For now, thousands of Syrian families are facing dangerously dipping temperatures on the border as they wait to see whether Turkey will open its borders.

"It keeps raining, and snow is expected," Burak Karacaoglu, a Turkish aid worker, said Sunday as he was preparing to cross the border into Syria to help those living in temporary shelters on the other wide. "We are facing the danger of people dying by freezing to death."

Among the few to make it from Syria to Turkey this weekend was Abdulnasser Al-Hamidi, a father of four who smuggled his family across the border. The family was briefly detained by Turkish officials who let the Syrians go after seeing their dire situation, Mr. Hamidi said on Sunday. The family fled their village near Aleppo on Friday, taking a little food and clothing for the journey.

"We didn't stay to see the damage," he said. "The last thing I saw was people walking in the rain, everyone fleeing. I can't bear to think about it."

Dion Nissenbaum in Istanbul and Nour Malas in Beirut contributed to this article.

(END) Dow Jones Newswires

February 07, 2016 20:15 ET (01:15 GMT)