The United States is looking for more tangible ways to support Syria's opposition and bolster a fledgling political movement that is struggling to deliver basic services after nearly two years of civil war, U.S. Secretary of State John Kerry said Wednesday.

Officials in the United States and Europe have said the Obama administration is nearing a decision on whether to provide non-lethal assistance to carefully vetted fighters opposed to Syrian President Basher Assad, and Kerry's comments indicated that the Americans are working to make sure that its aid doesn't fall into the wrong hands.

"We are examining and developing ways to accelerate the political transition that the Syrian people want and deserve," Kerry said.

"We need to help them to deliver basic services and to protect the legitimate institutions of the state."

The Obama administration is concerned about military equipment falling into the hands of radical Islamists who have become a significant factor in the Syrian conflict and could then use that materiel for terrorist attacks or strikes on Israel. But they're equally fearful that Syrians tired of constant instability will lose faith in an opposition that can do little to improve their daily lives.

Assad "needs to know that he can't shoot his way out of this, and we need to convince him of that, and I think the opposition needs more help in order to do that," Kerry said.

A decision whether to vastly increase the size and scope of assistance to Assad's foes is expected by Thursday when Kerry will attend an international conference on Syria in Rome that leaders of the opposition Syrian National Coalition have been persuaded to attend, the officials said. They spoke on condition of anonymity because the shift in strategy has not yet been finalized and still needs to be co-ordinated with European nations, notably Britain.

France, Syria's former colonial ruler, has been among the strongest supporters of the Syrian opposition, and French President Francois Hollande was the first Western leader to recognize their leadership.

"We agree all of us on the fact that Mr. Basher al-Assad has to quit," said French Foreign Minister Laurent Fabius.

U.S. may send food, medical aid

The U.S. does not plan to send arms to anti-Assad fighters, but is considering sending millions of dollars worth of food and medical aid. (Goran Tomasevic/Reuters)

Officials in Washington said the United States was leaning toward providing tens of millions of dollars more in non-lethal assistance to anti-Assad fighters, including vetted members of the Free Syrian Army who had not been receiving direct U.S. assistance.

So far, assistance has been limited to funding for communications and other logistical equipment, a formalized liaison office and an invitation to opposition coalition leader Mouaz al-Khatib to visit the United States in the coming weeks. It could be expanded to include pre-packaged meals and medical supplies.

The officials stressed, however, that the administration did not envision American military training for anti-Assad fighters nor U.S. provision of combat items such as body armour that the British are advocating.

Syria's opposition gets most of its arsenal from capturing government bases, but it's also believed arms have been provided by allies in Qatar, Turkey and Saudi Arabia.

UN refugee chief warns Syria faces a 'moment of truth'

Also Wednesday, the UN humanitarian chief warned that the growing number of Syrians fleeing the country's increasingly brutal conflict — now 4 million and rising every day — is outstripping the international community's ability to help.

Valerie Amos told reporters after briefing the Security Council that "this is a crisis that is completely stretching our capacity."

She said she is extremely concerned about the rising cost, noting that the UN has received only $200 million of the more than $1.5 billion pledged for Syria at a Jan. 30 donor's conference in Kuwait.

The $1.5 billion was supposed to cover humanitarian needs in Syria for six months but that projection, from the end of the year, is already out of date, she added.

"I think the first two months of this year have been a real game-changer," Amos said. "It demands more of us in terms of our ability to scale-up our operations, but ... even with us working full-tilt, the scale is out-pacing whatever we do on the response side."

On a positive note, she said, her office has been able recently to cross "conflict lines" between opposition and government-controlled areas to help people in need in the cities of Homs and Idlib. But the Syrian government is still refusing to allow aid to enter from Turkey, leaving thousands of people trapped without aid, she said.

UN refugee chief Antonio Guterres, who joined Amos during her address to the security council, told international ambassadors that a "moment of truth" was approaching in Syria and that the international community must not allow the situation to deteriorate further, according to quotes released by his office.

"What is happening in Syria today risks escalating very quickly into a disaster that could overwhelm the international response capacity — political, security-related and humanitarian," he warned. "This must not be allowed to happen."

Guterres noted that in April 2012, about a year after the conflict began, there were 33,000 registered refugees in the region.

As of Monday, he said, his office had registered or given registration appointments to 940,000 Syrians across the Middle East and North Africa. Since early January, he said, more than 40,000 people had fled Syria every week.