South Sudan rebels dismiss massacres

Rebels in South Sudan have rejected UN reports they had massacred hundreds of civilians as 'lies', as they wrested another town from government troops in a worsening civil war.

The rebels seized the town of Bentiu last week, unleashing two days of ethnic slaughter as they hunted down civilians sheltering in mosques, churches and a hospital, butchering dozens on the roadside, according to the United Nations.

But rebel spokesman Lul Ruai Koang praised the 'gallant forces' of the insurgents, who the UN said took to the radio to urge men to rape women from the opposition ethnic group and drive out rivals from the town.

'The government forces and their allies committed these heinous crimes while retreating,' Koang said, adding that the rebel offensive targeting oil fields was continuing.

However, the UN said the killings continued for almost two days after the rebels issued a statement boasting of victory in Bentiu, a time when Koang previously said gunmen were 'mopping and cleaning up' in the town.

South Sudan's army has been fighting rebels loyal to sacked vice president Riek Machar since the unrest broke out more than four months ago.

The scale of killings in Bentiu is one of the worst atrocities in the four-month conflict.

Toby Lanzer, the top UN aid official in the country, told AFP after visiting Bentiu he had witnessed the 'most terrible sight'.

'There are piles of bodies lining the streets where they had been executed, in the market, outside and inside places of worship... the majority wearing civilian clothes,' Lanzer said on Monday.

The US has threatened sanctions against those responsible for continuing the war.

The US ambassador to the UN Samantha Power said Tuesday that 'all responsible for South Sudan horrors and deliberately targeting civilians must be held accountable'.