"This figure represents nearly a doubling of the funds made available tothe humanitarian crisis in South Sudan. It is significant and it will save
lives," said Norwegian Foreign Minister Børge Brende at the close of the conference.
The sum raised in the meeting -- described as the "last chance to prevent famine" by the United Nations -- was in addition to $536 million (391 million euros) already pledged, yet remained $660 million short of the $1.8 billion the United Nations says the country needs.
"The outcome has surpassed our expectations," UN Humanitarian Affairs coordinator Baroness Valerie Amos said, adding that it had not been expected that the conference would deliver the full target figure.
"I think it will be difficult to raise the additional resources required... We are facing massive humanitarian crises in the world", she said, citing the examples of Syria and the Central African Republic.
According to the UN, four million people -- one third of the population -- are at risk of starvation in the young African state, ravaged by a conflict between rebel groups and the government since December 15.
On Tuesday, the US pledged $291 million, Britain $100 million and the European Union 55 million euros. Host country Norway promised $63 million.
The situation has become more critical with the imminent arrival of the rainy season, which will render the few existing roads and some landing strips unusable, complicating the distribution of aid to vast areas of the country.
"There are very many areas in South Sudan that are not accessible by road. It's because of the very weak infrastructure, the rain season, but it is also difficult to cross (front) lines in some areas," deputy director of the World Food Programme Elisabeth Rasmusson told AFP.
"Aid is extremely urgent because we know that 3.7 million people are facing a food crisis and emergency today. We know that the prospect is that it will escalate to 4 million people by August.
We have to reach these people because otherwise, we are going to see people dying of starvation."
Cholera cases have also been reported in the region with nine deaths out of 138 recorded cases according to the World Health Organisation.
At least 50,000 children are at risk of dying of malnutrition by the end of the year, according to UN childrens' agency UNICEF.
"Many are already resorting to eating wild foods such as bulbs and grasses," the agency said in a statement.
South Sudan became independent in 2011 after a long and bloody war between Sudan and the Sudan People's Liberation Movement (SPLM) rebel group currently in power.
However peace was short-lived as ethnic conflict between its two main groups, the Dinka and Nuer following a dispute between President Salva Kiir and his former vice-president Riek Machar erupted in July 2013.
Despite signing a peace agreement on May 9, hostilities have continued, resulting in massacres and atrocities against thousands of civilians from both sides. More than 1.3 million people have been displaced and many are living in extremely cramped and precarious conditions.
More than 325,000 of them have crossed the border seeking refuge in Ethiopia, Kenya, Sudan and Uganda, "countries which are already vulnerable for a variety of reasons", Amos said.
"We need more than funding, we need political will...," she added.
Amos and others at the conference called on the warring factions to respect a ceasefire agreement in place, avoid civilian casualties and facilitate aid organisations' movements in the region. Peace talks in Addis Ababa, intended to find a political solution to the conflict, were adjourned for 12 days starting on Monday.