(File image) United Nations Secretary General Ban Ki-moon

United Nations - Secretary-General Ban Ki-moon will tell the U.N. General Assembly later on Tuesday that Syria's humanitarian situation is “grave and deteriorating” and that the international aid response has been constrained by a lack of funding, his spokesman said.

Ban is due to brief the world body's 193 members on Syria's 17-month conflict along with the new U.N.-Arab League mediator, Lakhdar Brahimi, who took up the role on Saturday and described his bid to broker peace as “nearly impossible.”

“The secretary-general will discuss recent developments and call for support for (Brahimi's) work,” Ban's spokesman, Martin Nesirky, told reporters. “At the same time he will say that the humanitarian situation is grave and deteriorating both in Syria and in neighboring countries affected by the crisis.”

“We are constrained by underfunding,” Nesirky said. “The $180 million humanitarian response plan is only half-funded. He will also say that governments who have generously opened their borders and accepted their responsibility to shelter those who have sought refuge urgently need support.”

Syrian President Bashar al-Assad pledged on Tuesday to allow the Red Cross to expand its humanitarian operations. The United Nations has said that more than 235,000 Syrian refugees have registered in Iraq, Jordan, Lebanon and Turkey, while about 1.2 million people have been displaced within Syria.

As Syria spirals deeper into civil war, the U.N. Security Council has been paralyzed on taking strong action as Russia and China have blocked three Western-backed resolutions that criticized Assad and threatened sanctions. A council meeting on Thursday on the crisis achieved nothing new.

Turkey has repeatedly urged the United Nations to protect displaced Syrians inside their country, but creating a buffer zone for displaced Syrians would be difficult because a Security Council resolution would be needed to set up a no-fly zone, and Russia and China would not approve such a move, diplomats said.

Veteran Algerian diplomat Brahimi replaced Kofi Annan as the international mediator on the Syrian conflict. Annan had blamed the Security Council impasse for hampering his six-month bid to broker peace and leading to his decision to step down.

The United Nations says nearly 20 000 people have been killed in the conflict, which was sparked by a popular uprising against Assad. - Reuters