The World Refugee Council (WRC) has said nations have not done enough to help Uganda and her neighbors shoulder "the South Sudan humanitarian tragedy.'
The body said nations must "share the responsibility for protecting refugees, assisting host communities and providing robust support."
On June 22-23, Uganda will host the solidarity summit on refugees, jointly organized with the UN Refugee Agency, mainly to raise more cash to manage the crisis.
The newly-formed WRC convened for the first time in Geneva, Switzerland this week to consider the solutions to the global refugee crisis.
"The situation of South Sudanese refugees is symptomatic of deeper problems in the refugee system that the Council will seek to address," it said in a statement on Wednesday.
Since December 2013 when the civil war broke out, at least two million people have fled the world's youngest nation. Almost the same number has been internally displaced.
Half of those who have fled are in Uganda, which has been praised for having an accommodative refugee policy, with the country now hosting more than 900,000 South Sudanese refugees, according to the United Nations High Commission for Refugees (UNHCR).
The number is likely to be more than a million by end of the year. The country allows refugees to work and travel freely, access Ugandan social services and gives them a plot of land to live on, and another to farm.
While Ugandans are supportive of this gesture, the fear is that as more refugees stream into the country it may be hard to provide all the assistance needed, including land.
President Museveni told an Inter-governmental Authority on Development (IGAD) summit in Nairobi in March that "whereas Uganda's liberal policy of providing land is praised, it is not sustainable as land can only be provided if available."