South Sudan President Salva Kiir has reappointed bitter rival Riek Machar as vice-president as part of a peace deal aimed at ending more than two years of war, state television reported.

The civil conflict erupted in December 2013 after Mr Kiir accused Mr Machar of plotting a coup.

Since then thousands have died and more than two million have been displaced.

South Sudan is the world's youngest country and one of the least developed. It split from the North in 2011.

Amid a threat of sanctions from the UN, the two sides signed a peace deal in August last year.

Fighting was supposed to stop immediately but there have been frequent violations.

The men also agreed to share out ministerial positions, and a presidential decree read out on state television confirmed Mr Machar's reappointment.

It returns the government to where it was before the war broke out.

Mr Machar, who is not currently in South Sudan, has welcomed the move, telling the BBC he could return within three weeks if security arrangements were implemented.

"I'm eager to ensure that peace returns to the country, political stability is maintained, the permanent peace is respected - I'm confident we can do this," he said.

The UN and African Union have accused both sides of carrying out atrocities - last month an AU-backed report alleged that 50 civilians had suffocated after government troops locked them in a shipping container.

READ: South Sudan troops accused of suffocating 50 people in container

But that accord has repeatedly broken down and a UN report last month said both leaders qualified for sanctions over atrocities in the conflict.

The decree read out on state TV said Machar would be first vice president, his position before he was sacked in 2013, the move that eventually triggered the violence. There was no immediate announcement from Machar.

Oil-producing South Sudan split away from Sudan in 2011 amid mass celebrations and promises of aid and good will from most of the developed world.

But its regional and Western backers were dismayed when fighting erupted, often along ethnic lines.

Last month's confidential report by a UN panel that monitors the conflict in South Sudan for the Security Council stated that Kiir and Machar were still completely in charge of their forces and were therefore directly to blame for killing civilians and other actions that warrant sanctions.

According to the report, those violations include extrajudicial killings, torture, sexual violence, extrajudicial arrest and detention, abductions, forced displacement, the use and recruitment of children, beatings, looting and the destruction of livelihoods and homes.

The report described how Kiir's government bought at least four Mi-24 attack helicopters in 2014 from a private Ukrainian company at a cost of nearly $43 million.

READ: Arms flows to South Sudan rivals revealed in UN report

It added that Machar's forces were trying to "acquire shoulder-fired anti-aircraft missiles to counter the threat of attack helicopters, specifically citing the need to continue and indeed escalate the fighting."