U.N. Secretary-General Ban Ki-moon opened the gathering by calling for an end to the fighting "in the name of humanity," yet noted that the violence shows no signs of easing and that the refugee exodus to places like Turkey and Jordan could intensify.
Jordan's economic council said the country was already near the breaking point. The kingdom has spent more than $833 million on aid for refugees accounting for nearly half the estimated 700,000 people who have fled Syria and that it was unable to sustain a financial burden that has so far siphoned off about 3 percent of its GDP. Some U.N. officials say the refugee figures could approach 1 million later this year if the conflict in Syria does not ease.
Speaking at the U.N.-led gathering in Kuwait, Jordan's King Abdullah II said sheltering and assisting the wave of refugees is above the country's "capacity and potential."
"We have reached the end of the line. We have exhausted our resources," he said.
Last week, the king amplified his appeal for international help at the World Economic Forum in Davos, Switzerland, saying "the weakest refugees are struggling now just to survive this year's harsh winter" and up to 3,000 a day are still crossing the Syria-Jordan border.
Ban used his opening remarks Wednesday to urge all sides "and particularly the Syrian government" to halt attacks in the 22-month-old civil war that the U.N. says has claimed more than 60,000 lives.
"In the name of humanity, stop the killing, stop the violence," Ban told envoys from nearly 60 nations, including Russia and Iran, key allies of Syrian President Bashar Assad's regime.
Aid officials estimate that more than 2 million Syrians have been uprooted or are suffering inside the country as the conflict widens - including what peace envoy Lakhdar Brahimi called "unprecedented levels of horror" in an address to the U.N. Security Council after at least 65 bodies were found Tuesday in a what appeared to be a mass killing in Aleppo.
Before the latest donors' conference, Ban described the international humanitarian response to Syria as "very much limited" in comments to the official Kuwaiti News Agency.
But the meeting leveraged more pledges. Kuwait's ruler, Sheik Sabah Al Ahmad Al Sabah, promised $300 million in a move that was quickly matched by Gulf partners Saudi Arabia and the United Arab Emirates, which are all major backers of Syrian rebel factions. Ban said additional donations on Wednesday included $184 million from Gulf non-government groups and charities.
On Tuesday, the European Union and the U.S. promised a total of nearly $300 million.
The head of the U.S. delegation, Assistant Secretary of State Anne Richard, lauded the donations from Gulf nations, which often bankroll their own aid efforts but are not traditional top donors to U.N. programs. She noted, however, that the humanitarian funds are only to deal with immediate needs over the coming months.
"It's good for now, but predictions are that it's not going to be over soon," said Richard, who deals with refugee and migration affairs.
Ban described the situation in Syria as "catastrophic and getting worse by the day."
He listed a "cascading catalog of horrors" facing Syrians, including shortages of food and medicine and abuses such as "sexual violence and arbitrary arrests and detention." Half of public hospitals have been damaged, he added.
"The use of heavy weapons in residential areas has destroyed whole communities and neighborhoods," Ban told delegates.
While international aid channels are open to refugee camps in places such as Turkey and Jordan, there is far more limited capacity to organize relief efforts inside Syria where hundreds of thousands more are internally displaced people because of the fighting and obstacles from Assad's regime.
Paris-based Medecins Sans Frontieres, or Doctors Without Borders, said the U.N. and others need to open more routes for aid to reach rebel-held areas, which now receive only a "tiny share" of international humanitarian help.
"The current aid system is unable to address the worsening living conditions facing people who live inside Syria," MSF president, Marie-Pierre Allie, said in a statement.
The escalating hardships in camps outside Syria also can be used by Assad's government as potential fodder in its claims that rebels are responsible for the country's collapse, said Fawaz Gerges, head of the Middle East Center at the London School of Economics.
"The misery of the refugees, their suffering in neighboring countries, provide the ammunition for Assad, who is saying to them, 'See, you have no one else but your country, so come home,'" Gerges said.