NEW YORK - The head of Syria's opposition told US Secretary of State John Kerry on Thursday the country's situation was "desperate" and called for the United States to arm the rebels quickly and to push harder for a political settlement.

The United Nations says more than 100,000 people have been killed since Syria's civil war erupted more than two years ago pitting President Bashar al-Assad's forces against rebels seeking to end his family's four-decade rule.

President Barack Obama, having withdrawn US troops from Iraq and seeking to wind up the US war in Afghanistan, has been reluctant to get involved in the conflict in Syria.

However, US congressional panels this month agreed to a White House plan to provide arms to the rebels despite lawmakers' questions about its chances of success and concerns the arms might be used against Western targets.

A US official has said funding for the classified program runs out on Sept 30, when the US fiscal year ends. That means the White House will have to seek Congress' blessing again for arming the rebels, the official said, possibly setting up a renewed confrontation over Washington's policy on Syria.

"The US commitment of military support to the Supreme Military Council is vital, but it needs to happen fast, and in a way that allows us to defend ourselves and protect civilians," Ahmed al-Jarba, the Syrian National Coalition's newly elected leader, said in a statement released as he met Kerry in New York.

"The situation in Syria is desperate. We urgently need American action to push the international community to demand a political transition," he added. "American leadership and drive is essential to end this war and bring the democracy that the large majority of the Syrian people want."