“The catastrophic situation demands massive and urgent international aid,” said Jacques Diouf, head of the UN Food and Agriculture Organisation (FAO), which hosted Monday’s emergency meeting of UN aid agencies and charities in Rome.

“It is imperative to stop the famine,” said Diouf, after the United Nations this month declared a famine in two insurgent-held areas of southern Somalia.

The UN World Food Programme (WFP) also announced at the talks that it would begin an airlift of food aid on Tuesday into the Somali capital Mogadishu, as well as to eastern Ethiopia and northern Kenya on the border with Somalia.

An estimated 3.7 million people in Somalia — around a third of the population — are on the brink of starvation and millions more in Djibouti, Ethiopia, Kenya and Uganda have been struck by the worst drought in the region in 60 years.

Officials said at Monday’s meeting that the UN has received some $1.0 billion (696 million euros) since first launching an appeal for the region in November 2010 but needs a billion more by the end of the year to cope with the emergency.

The World Bank on Monday pledged more than $500 million, with the bulk of the money set to go towards long-term projects to aid livestock farmers while $12 million would be for immediate assistance to those worst hit by the crisis.

French Agriculture Minister Bruno Le Maire said that donor countries would hold talks to step up aid pledges in the Kenyan capital on Wednesday and called for action to crack down on high food prices on international markets.

“If we don’t take the necessary measures, famine will be the scandal of this century,” Le Maire said. He also berated the international community for having “failed” to ensure food security in a world affected by climate change.

UN officials say the drought has killed tens of thousands of people in recent months, forcing hundreds of thousands of desperate survivors from the worst-affected areas of Somalia to walk for weeks in search of food and water.

The key challenge for aid groups has been reaching parts of southern Somalia held by the Al Qaeda-inspired Islamist militia group Shebab, which has banned WFP and other international humanitarian agencies from operating on its territory.

“The fundamental cause of the famine that has so suddenly created devastation for the Somali people is the fragility of the state and the enduring conflict,” Somali Deputy Prime Minister Mohamed Ibrahim told the conference.

Ibrahim called for “humanitarian corridors” to reach the affected areas.

WFP chief Josette Sheeran said her organisation would begin food airlifts on Tuesday into Mogadishu, as well as aid flights to Dolo in Ethiopia on the border with Somalia and to Wajir in northern Kenya, which has been badly hit by drought.

The plight of children in Somalia is “the worst I have ever seen,” she said, after visiting Mogadishu and the Dadaab refugee camp in Kenya over the weekend.

“What we saw is children who are arriving so weak that many of them are in stage four malnutrition and have little chance — less than 40 percent chance — of making it,” Sheeran said.

“We also heard from women who had to leave babies along the road and make the horrifying choice of saving the stronger for the weaker or those who had children die in their arms,” she added.

“These children are extremely weak. It is the worst I have ever seen.”

Live Aid organiser and Irish rocker Bob Geldof meanwhile joined activists in urging the international community to come up with more aid for famine victims, in a letter published on Monday ahead of the meeting in Rome.

Geldof and other celebrities accused France, Germany, Italy and Arab states of having “so far given minuscule amounts of money to prevent people dying from hunger” in the letter, organised by U2 band frontman Bono’s charity ONE.

Barbara Stocking, the director of Oxfam, said the crisis was “shameful”.

“We have not had the investment in small producers across the world that was expected… The money has simply not come through,” she said.

“Often it feels as if the donor community is prepared to be very generous when it comes to this crisis but is simply not prepared to commit to the longer term.”