Turkey has sealed off its border with Syria for two days after intense bombing has spread into the countryside and whittled away the rebel-held city.
Already 20,000 Syrians are at the Bab al-Salam border crossing and another 50,000 are on their way, an official with the Turkish disaster agency AFAD.
It follows 10,000 people rushing to each northern city Azaz and Afrin, just north of Aleppo and closer to the Turkish border.
Aid agencies in southern Turkey are frantically trying to help the people massing at the Bab al-Salam border crossing following the most sustained assault on the area in the five years since the civil war began.
Turkish Prime Minister Ahmet Davutoglu said they would continue to feed and shelter the refugees in the towns of Azaz and Afrin in north-western Syria, but did not say when or if they would be allowed in.
Turkey is the starting point for thousands of migrants wanting to reach Western Europe, with groups crossing to Greece on boat, before travelling through borders in eastern Europe.
But Sherif Elsayed-Ali, deputy director of global issues at Amnesty International, said: “Turkey must not close its doors to people in desperate need of safety.
“These people have fled airstrikes and heavy fighting; they are likely to be traumatised and exhausted. Turkey must allow them to enter