The UN was also scrambling to find replacement troops for its peacekeeping mission on the Golan Heights after heavy fighting between Syrian forces and rebels on Thursday prompted Austria to announce it was pulling out.
The world body said yesterday that a total of USD 3.8 billion is needed to help Syrian refugees who have spilled across the country's borders to escape fighting at home.
The figure for operations inside Syria was put at another USD 1.4 billion.
"It is not only a matter of generosity but also of enlightened self-interest."
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More than 94,000 people have been killed and some 1.6 million Syrians fled the country since the civil war began in March 2011 after President Bashar al-Assad's cracked down on protests against his regime, according to The Syrian Observatory for Human Rights.
The number of refugees is expected to reach at least 3.45 million by the end of this year, according to the UN appeal.
Government forces were trying yesterday to mop up final pockets of rebel resistance north of Qusayr, the central town near the border with Lebanon that they retook on Wednesday bolstered by fighters from Lebanon's Shiite movement Hezbollah.
At the United Nations, Russia agreed to a Security Council statement demanding that its ally Syria allow humanitarian access to Qusayr.
The Observatory said the army was bombarding another rebel bastion to the north of Qusayr to which hundreds of wounded and civilians had fled.