Juba — President Salva Kiir Mayardit instructed South Sudan's army chief on Tuesday during a speech in Juba to investigate and hold accountable soldiers accused of committing abuses against civilians in Jonglei state.

President Kiir said the fact that civilians are deserting towns where the national army lives, preferring to take refuge in the bush means that "there is something wrong."

"We can't say that we at peace when there is a rebellion in Jonglei state," said Kiir at the 8th commemoration of South Sudan's Martyrs Day ceremony conducted at John Garang Mausoleum in the capital Juba.

Human Right Watch and other groups accuse South Sudan's army, the Sudan People's Liberation Army (SPLA), of targeting members of the Murle ethnic group in Pibor county, where the armed forces are fighting an insurgency led by David Yauyau.

The rebel leader and most of his rebellion come from the cattle herding Murle ethnic group.

Yauyau launched his armed rebellion against the Juba government after his bid to become a Jonglei MP in the April 2010 elections, loosing to the candidate from the SPLM, South Sudan's ruling party. He alleged that the vote was rigged.

MURLE ELDERS TO EQUALLY ACT

President Kiir offered an amnesty to different rebels groups in 2011 before South Sudan declared independence from Sudan, which Yauyau accepted. He was integrated into the army at the rank of Major General, despite having been a civilian before his rebellion.

However, in August 2012, he returned to the bush and renewed his war against the ruling SPLM, claiming to be fighting against nepotism, tribalism, discrimination against minority groups and corruption.

Juba alleges that Yauyau is being backed by the Sudanese government in order to destablise the young nation, which is hoping to strike oil in Jonglei state. The eastern state is also likely to host an alternative oil pipeline to the East African coast to bypass South Sudan's reliance on exporting its crude through Port Sudan on the Red Sea.

In a renewed presidential amnesty offered in 2013, rebels groups from Unity and Upper Nile states have returned to Juba but Yau Yau has so far declined the offer.

"The Murle elders and leaders here in Juba must speak to Yauyau (to accept the amnesty)," said Kiir.

Martyrs day, has been held on July 30, since the SPLM's leader John Garang died in helicopter crash while returning from Uganda on that day in 2005 just months after signing the peace that ended the two decade civil war and secured South Sudan's right to self determination.

As well as recognising Garang's role in the liberation struggle, the day is set aside to commemorate the estimated 2 million people who died during the civil war.