Several buses en route to evacuate ill and injured people from the besieged Syrian villages of al-Foua and Kefraya were attacked and burned on Sunday, the Syrian Observatory for Human Rights and Syrian state television said.

The United Nations Security Council is due to vote Sunday on a resolution aimed at ensuring that U.N. officials can monitor evacuations from besieged parts of the Syrian city of Aleppo.

Doctors Without Borders pleaded on Monday for access to treat the wounded in the rebel-held part of Syria's Aleppo.