The US-based International Rescue Committee (IRC) urged the world on Sunday to scale up planning and funding to help end the "staggering" humanitarian crisis in Syria, dpa reported.
"The Middle East is once again facing a human displacement tragedy," the refugee assistance organization said in a new report.
"Current assistance levels are drastically insufficient to address existing needs, let alone the barest requirements to respond to a lengthy humanitarian emergency and post-conflict recovery," it added.
More than 600,000 Syrians have fled the Syrian conflict to neighbouring countries like Turkey, Lebanon, Jordan and Iraq. The UN had anticipated that number could soon exceed one million if the exodus continues at its current pace of 3,000 refugees a day.
There are some 2 million civilians displaced in Syria and the UN has estimated that 4 million are in dire need of assistance.
The IRC report said that many refugees have cited rape as the main reason for leaving their villages in Syria.
On the ground, government forces claimed they have taken over much of the strategic rebel-held Daraya area on the outskirts of Damascus, inflicting heavy losses on rebel fighters.
"Government forces managed to kill and wound many foreign militants in Daraya in a major military offensive," state-run television reported.
Daraya is located near the district of Mezzeh, which is home a large military base, and is close to Kfar Soussa where most government headquarters are located. It is today home to some 3,000-5,000 rebel fighters, mainly Muslim extremists from al-Nousra Front, who are fighting alongside the Free Syrian Army across Syria.