ISLAMABAD (AFP) - The world has one last chance to give cash for Pakistan`s quake victims or else the United Nations will have to stop its vital helicopter flights and scale down food deliveries, aid officials said. "We need the cash to keep the helicopters flying," UN humanitarian coordinator for Pakistan Jan Vandemoortele told a news conference in Islamabad on Friday. "It is now or never, we will not have a second chance." Vandemoortele was referring to six UN choppers which form part of an international fleet of around 60 helicopters taking part in the mission to save survivors of the devastating October 8 earthquake. Pakistan itself, the United States, Germany, Japan, Britain and other countries are funding their own costly helicopter operations separately from the UN. "We can keep the helicopters flying for one week," World Food Programme (WFP) emergency coordinator Michael Jones told the same news conference, again referring to the UN choppers. The UN`s helicopter air bridge was an absolute priority with only around three weeks until winter snows completely cut off mountainous quake-hit villagers, Jones said. "If we don`t keep it running people will die," he added. Choppers have been the backbone of efforts to get tents, blankets and food to around three million people left homeless by the earthquake. More than 54,000 people were killed and 77,000 injured in the disaster. The UN said Thursday that key emergency aid operations for Pakistani earthquake survivors were still vastly underfunded, a day after donor nations promised about half a billion dollars more in overall assistance. Many of the pledges are for long-term reconstruction, while the UN says the cash is needed to save thousands of people from cold, hunger and disease in the next six months. "We need the money now, if not we will be forced to scale down some of our operations, including food delivery. So far we have been operating on reserves and we have been borrowing from wherever we could from existing funds and projects," Vandemoortele said. "Tomorrow will be too late for thousands and thousands of victims, especially babies, small children vulnerable to pneumonia, malaria, malnutrition," he added. "This is not the moment to pledge more money, this is the moment to contribute." The WFP`s Jones said it currently had enough food to cover 500,000 people for two months. "However we have 2.3 million estimated to be in need, that 500,000 represents a very small proportion," he added.