At least 47 people have been killed since the Islamic State (IS) began its siege of al-Yarmouk Palestinian refugee camp, the Syrian Observatory for Human Rights (SOHR) reported on Thursday.

At least 32 of the fatalities were members of IS, Aknaf Beit al-Maqdis -- a Palestinian group opposing the Bashar al-Assad regime -- and other Syrian rebel militias battling IS inside the camp, Efe news agency reported citing SOHR.

Ten of the victims were civilians, including one who starved to death and another who did not have access to medical care, and five Syrian regime soldiers were killed in clashes.

Fighting continues in al-Yarmouk -- military helicopters dropped 11 barrels bombs on Wednesday night, raising the total number of explosive barrels released on the camp to 36.

SOHR asserted that IS and the Al Qaeda-affiliated Nusra Front together control 90 percent of the camp.

Around 18,000 of the 160,000 Palestinians once living in the camp stayed on after the outbreak of the Syrian conflict in March 2011, although the number is dwindling.