BEIRUT (Reuters) - Syria's civil war is unleashing a "staggering humanitarian crisis" on the Middle East as hundreds of thousands of refugees flee violence including gang rape, an international aid agency said on Monday.

Rape is being used as a weapon of war in the Syrian conflict to such an extent that many refugee families are citing it a as a primary reason to flee, according to a new report.

DAMASCUS, Syria, Jan. 14 (UPI) -- The level of aid in Syria is insufficient and foretells of a huge humanitarian disaster that will demand more planning and funding, a rights group said Monday.

Rape and other forms of extreme sexual violence in Syria, often committed in front of family members, is a major reason for increasing numbers of people to flee their homeland, the International Rescue Commission said.

DAMASCUS (AFP) An air strike on a rebel town near Damascus on Monday killed 13 women and children, a watchdog said, fuelling growing international calls for a war crimes probe into the 22-month Syrian conflict.

(CNN) -- Sharifa lost her foot when the Syrian jets swooped down and fired missiles at the house. Now the hijab-clad girl sits jaded in a dirty, hardscrabble displaced persons camp near Turkey, growing up fast, confused and far from home.

As the death toll continues to grow steadily in Syria, an aid agency working in the conflict zone has said that doctors are being murdered to stop wounded getting treated.

The Middle East faces a "staggering" humanitarian crisis caused by the conflict in Syria, an aid agency says. With more then 600,000 Syrians having fled the country, the International Rescue Committee is calling on the outside world to step up its response.