New refugee camps are being built along the Syrian border with Turkey to house thousands of people who have fled the northern city of Aleppo.
Syrian government forces, backed by Russian airstrikes, have been fighting opposition fighters in the former key industrial city.
Turkish officials say about 77,000 people are sheltering in camps built along the Turkish border.
The Turkish Prime Minister says they will only be allowed to cross when necessary.
There are currently tens of thousands of people on the Turkey-Syria border waiting on world leaders to decide their fate.
Turkey has been praised for taking in more than 2.5 million refugees from Syria.
Now, only those seeking emergency help can pass through.
But Deputy Manager of the Turkish Red Crescent, Kerem Kinik, says they remain committed to helping asylum seekers.
(Translated)"Our local governor is sticking to the government's latest decision to host Syrians on the other side of the border. Our work is to maintain supplies for people's needs at their location. We will improve conditions of the camps on the other side in a short time of period. We will try to support basic needs such as food and health."
It's been three days since asylum seekers began to arrive.
200 tents were set up on day one and aid workers say they have about 50 more to do.
One asylum seeker woman says they're running out of options.
"Where should we go? Our region, Zahra, is demolished. Everybody died or left. We are pushed on one side by Bashar (al-Assad), on the other hand Kurds and Daesh. Where should we go? The door should be open for us."
Turkish Prime Minister Ahmet Davutoglu says that will happen when it's necessary.
"Nearly 30,000 people have amassed near our border. We will meet the needs of our Syrian brothers as usual. We will take them in when necessary. We have expressed our stance on this matter clearly. But nobody should excuse or tolerate Russian air strikes that are clearly an ethnic massacre."
German Chancellor Angela Merkel is in the Turkish capital for talks.
She says she's horrified by the suffering in Syria, but insists it's important to control migration to prevent potential enemies and people smugglers getting to Europe.
(Translated)"We want to stop illegal immigration, but we obviously have to be ready to accept refugees by legal means, especially Syrian refugees. This is the so-called contingent system and our experts, together with the European Union and representatives from the European Commission, will work very intensively over the coming days to see what something like that can look like in practical terms."
Germany received an unprecedented 1.1 million asylum seekers in 2015, with most fleeing the conflicts in Syria, Iraq and Afghanistan.
But as leaders discussed ways to better control the borders, reports emerged that more than 30 bodies were found after their vessel sunk en route from Turkey to Greece.
Meanwhile, new claims about the situation for civilians inside Syria have been revealed.
UN investigators have published a report calling the treatment of detainees in Syria a crime against humanity.
The chairman of the Independent Commission of Inquiry on Syria, Paulo Pinheiro, says the government is deliberately exterminating civilians.
"The mass scale of deaths of detainees suggests that the government of Syria is responsible for acts that amount to extermination, as a crime against humanity, because these deaths are brought about in pursuance of a state policy to attack the civilian population. Prisoners are routinely tortured and beaten, forced to live in unsanitary and overcrowded cells, with little food and no medical care, many perish in detention."
He says anti-government armed groups have also committed violations against their detainees, with government soldiers and members of rival armed groups executed, or dying after being tortured.
World leaders are reassessing their role in the Syrian crisis.
Canada is withdrawing six jets that have been bombing targets in Iraq and Syria.
Canadian Prime Minister Justin Trudeau says two surveillance planes will remain in the region, and they will continue to help refuel aircraft.
"There is a role for bombing, particularly in the short term. But Canada has many advantages, including hard-earned abilities on training local troops, that we gained through ten years in Afghanistan and in other theatres (of war) where we can actually offer the best help, in a different way. That is what we are doing and I am extremely confident that this mission not only is better than our last mission but it's the right thing to do."
