Opposition groups are trying to break army blockades across Syria, including rebel-held areas of the capital Damascus.
For almost a year, a number of Damascus suburbs have been choked by government forces, cutting off food and medicine from many residents.
Relief organisations say more than four million Syrians lack enough food across the country.
Aid agencies are warning of the risk of mass starvation.
Al Jazeera's Zeina Khodr reports from Beirut.