A global emergency delivery service that has kept tons of humanitarian aid flowing despite coronavirus travel restrictions could shut down next month if funding can't be found to keep it running, the World Food Program warned Friday.

"Unless a substantial injection of funds is provided by donors by the end of the first week of July, WFP will have no choice but to ground most of its humanitarian air fleet by the end of July," WFP spokeswoman Elisabeth Byrs told reporters. While, the flights was planned to run for about three to four months or even longer in the first place.

The World Food Programme (WFP), which runs the flight network, said that only 178 million U.S. dollars (159 million euros) of the 965 million U.S. dollars common services budget needed to operate the service throughout 2020 had so far been advanced or confirmed by donors.

WFP sent a first plane on April 30 loaded with medical supplies for developing nations especially vulnerable to the coronavirus pandemic, aiming to ramp up the service to 350 flights per month. 

As the coronavirus crisis continues around the world, the network is operating on an unprecedented scale.

The emergency delivery service has been key in shipping tons of aid for the pandemic and other crises like HIV and cholera that need drugs and vaccines to keep flowing. The UN and various health entities have openly worried about dangerous delays in many countries' vaccination campaigns, saying the lives of up to 80 million children under the age of one could be at risk.

So far, the World Food Program emergency service has completed 375 cargo and passenger flights, delivering more than 2,500 aid workers with "enough cargo to fill 120 jumbo jets waiting to be transported in coming weeks," the WFP said.

"It would be a very bad situation if the vulnerable people don't get this assistance," said Byrs.

The flight network relies on three central hubs: Guangzhou in China, Liege in Belgium and Dubai in the United Arab Emirates, sited because they are close to the factories where humanitarian supplies are manufactured.

Aid is then flown out to a handful of regional hubs, namely Kuala Lumpur, Panama, Addis Ababa, Accra and Johannesburg, before moving on to hundreds of smaller destinations.

Though regular commercial passenger and cargo flights are slowly resuming and it is possible to use some of their spare capacity for transporting aid, Byrs said that there were no commercial flights going to some of the impoverished destinations that UN aid needed to reach.

(With input from AP and AFP)