A group of UN experts tasked with forecasting the next disasters likely to require billions of dollars in humanitarian aid has warned of deepening crises in global hotspots from Burundi to Afghanistan over the next six months.

In an unusually frank assessment for a UN publication, the six-monthly "Alert, Early Warning and Readiness Report" said Libya could fall apart, Burundi could see another coup, Islamist militants would gain territory in Afghanistan and Mali, and Ethiopia would not have enough food to cope with its drought.

In Libya, the United Nations is trying to finalise a political agreement to unite two rival governments. The report said failing to do so would be likely to cause a split between Libya's internationally recognised government and the army, opening the way for a military takeover.

"In the absence of a legitimate government, Libya is likely to face a rapidly deteriorating civil war, losing any chance of achieving stability or a political solution in the foreseeable future," it said.

Elsewhere in Africa, Nigeria and its neighbours will struggle to stop more massacres by Boko Haram militants, while their armies will continue to commit abuses, it said.

"Apart from Boko Haram, the regional armies similarly perpetrate human rights violations against civilians, including extrajudicial killings, enforced disappearances, acts of torture and rape," the report said.

There is too little peacekeeping muscle to defend government territory in Mali and to ensure security in Central African Republic, where armies on both sides of the sectarian divide are trying to unseat President Catherine Samba-Panza, it said.

Humanitarian work around the globe will remain underfunded, constrained or under attack, including in Afghanistan, where a US airstrike hit a Medecins Sans Frontieres hospital last month.

"As the attack on the MSF hospital in Kunduz highlights, the humanitarian access for aid workers is worsening," it said.

In a rare case of easing tensions, the report said the conflict in Ukraine would de-escalate or remain frozen, partly because Russia's military involvement in Syria would reduce its involvement in eastern Ukraine, where pro-Russian separatists have been battling Kiev's forces.

The political risks the report lists are likely to increase the number of people globally needing humanitarian aid by as much as 1.9 million, it said. But that is still far fewer than those likely to need help coping with natural disasters, especially the El Nino weather phenomenon, the report added.

El Nino is forecast to force 500,000 people in the Horn of Africa to seek international food aid, while a further 4.1 million are at risk in the South Pacific Islands as well as several million more in southern Africa. – Reuters