ALEPPO, Syria, Dec. 7 (UPI) — Syrian President Bashar al-Assad’s regime on Wednesday captured Aleppo’s Old City after rebels retreated — giving the government control of three-quarters of east Aleppo, a human rights group said.

Rebels first captured east Aleppo four years ago and made it a stronghold. The Syrian Observatory for Human Rights said rebels retreated from the Old City after a regime offensive captured the Bab al-Hadid and Aqyul districts.

Assad’s forces seized the Old City early Wednesday, increasing the likelihood the besieged rebels will be defeated as some debate whether to withdraw. Most rebel groups have agreed in theory to a withdrawal plan, but a small number of powerful hardline groups oppose it, The Washington Post reported.

After a pause in hostilities, Assad’s regime began a new offensive to capture east Aleppo on Nov. 15, which has caused more than 730 civilian deaths and has led 80,000 civilians to flee the section of the city. Rebels on Wednesday called on the United Nations to oversee a five-day cease-fire to carry out medical and civilian evacuations from the east, where there is a humanitarian crisis.

“People have flocked there and the system can’t cope. There are no resources, all day there is bombing,” said Col. Abo Bakr, a representative of a group allied with the Free Syrian Army.