The UN World Food Programme on Tuesday said it was airlifting supplies to northeastern Syria, where raging violence has made it nearly impossible to truck aid in.
"WFP started airlifting on Tuesday enough food to feed close to 30,000 displaced people for a month from Iraq to Qamishli in northeast Syria," spokeswoman Elisabeth Byrs said.
"This is for people who otherwise would be cut off from humanitarian assistance," she told reporters.
The agency plans to fly in more than 400 tonnes of food and other items, mainly clothes, detergent and soap, supplied by UN children's agency UNICEF and the International Organization for Migration.
In December, the WFP airlifted supplies for 62,000 in the northeast who had been deprived of food aid for more than five months.
The WFP's operation is the only airlift currently under way in Syria.
Aid agencies have repeatedly sounded the alarm about their inability to supply regular aid by road -- logistically simpler, but more dangerous -- to the millions of Syrians who have been driven from their homes over nearly three years of civil war.
At UN-brokered peace talks between the Syrian government and opposition in Geneva last week, the only tangible pledge to emerge concerned aid for civilians in rebel-held parts of the central city of Homs, besieged by the military since June 2012.
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But the warring sides have traded barbs over who is blocking an international aid convoy which agencies said had been standing ready for days.
UN agencies have steered clear of pinning blame, and repeatedly appealed for access to Syrians in desperate need.
"As of this morning, the convoy in Homs is not moving," said Jens Laerke, spokesman for the United Nations' humanitarian coordination arm.
He said aid agencies were "deeply frustrated and disappointed" that there had been little or no progress in last week's talks on bringing relief to Homs and elsewhere.
"We're now talking about over three million people in hard-to-reach areas, of whom 242,000 are in effectively besieged areas without any humanitarian access at the moment," Laerke told reporters.
He also spotlighted a glaring shortfall in responses to a UN appeal for $2.3 billion (1.7 billion) to fund Syria aid operations.
"It's funded now at 6.8 percent," he said.
The top three donors to date have been the United States with $92 million, Britain with $49 million and the European Commission with $14 million.