* Aid needs mount as conflict drags on
* Numbers needing aid "are terrifying" -UN refugee chief
Most of the contributions to the U.N.-led aid effort in Syria's two-year-long civil war have come from critics and enemies of Syrian President Bashar al-Assad, while his supporters Russia and China have given little, aid sources say.
The United Nations has been working off an estimate of $1.5 billion for its Syria funding needs, but that figure is already looking much too low, with refugee numbers far ahead of forecasts and no end in sight to the fighting.
U.N. High Commissioner of Refugees Antonio Guterres has said almost half of Syria's 20.8 million people will rely on aid by the end of 2013.
"These figures are terrifying," Guterres, head of the refugee agency UNHCR, warned the U.N. Security Council on Thursday.
The UNHCR says China so far has given $1 million for Syrian refugees in Turkey, while the U.N. World Food Programme (WFP), which already needs almost $20 million a week to feed Syrians, says it has not yet received anything from China.
Russia has given $2 million for UNHCR's operations worldwide and $7.5 million to WFP during since the Syrian conflict began.
The vast majority of the pledges and donations that the U.N. has received have come from Assad's critics, with Kuwait, the United States and European Union making the biggest donations.
Syria's neighbours Turkey, Lebanon, Jordan and Iraq have also borne a huge burden of refugees. Turkey has provided more than $750 million of assistance to refugees, Guterres said.
CHINA SAYS TAKES SITUATION SERIOUSLY
Asked to explain its comparatively low contribution to the U.N. appeal, Chinese Foreign Ministry spokeswoman Hua Chunying said on Friday that China was taking the humanitarian situation very seriously.
"We share in the suffering of the Syrian people. We have been taking practical actions to assist the Syrian people. China will continue to provide assistance to the Syrian people within our ability," she said, without giving any figures.
In Moscow, Russian Foreign Ministry spokesman Alexander Lukashevich said Russia provided aid to Syria through both international humanitarian organisations and bilateral channels.
"We are among the 20 biggest donors to Syria, with a volume of targeted contributions of more than $7 million in 2012. In the current year, Russia plans to earmark more than $3 million for these aims, and we provide solid humanitarian support to states bordering Syria," he told a weekly news briefing.
Russia and China, Assad allies, have been engaged in the so far fruitless diplomatic peace process for Syria, along with the United States, the European Union and several Gulf Arab states.
But senior U.N. officials are reluctant to suggest Moscow and Beijing should do more to sort out the humanitarian crisis.
"I would not say they are doing as much as they can, but I would not say they are not cooperating," said Rashid Khalikov, director of the Geneva office of the U.N. Office for the Coordination of Humanitarian Affairs.
Bruce Aylward, assistant director general of the World Health Organization, said the aid effort was based on a common obligation and no country had a particular duty to pay.
"We would be terrified if we would talk about apportioning moral responsibility for responding to the humanitarian crisis that we're facing, not just in Syria but in any situation," he told a news conference on Thursday.
"We're really looking for support across the board for this, and we are speaking very loudly to all communities, all countries, in trying to mobilise that support."
Aylward was the only one of nine senior U.N. officials at the news conference, which was called to laud Kuwait for making good on a $300 million pledge, to respond to a question about China and Russia's contributions to the U.N. appeal.
Guterres later told Reuters that he agreed with Aylward but declined to say China and Russia should pay more.
"We are asking everyone. And they gave the contributions they gave," he said, without elaborating.