South Sudan's rebel leader and ousted vice president has called on the Juba government to step down after accusing it of committing a genocide against its people. Riek Machar made the claim as the country is marking the third anniversary since war broke out on 15 December 2013.

Violence erupted when President Salva Kiir, of the Dinka ethnic group, fired his deputy Machar, from the Nuer group, from his cabinet.

Ethnic-related violence targeting Dinka and Nuer has caused the deaths of at least 50,000 people, amid allegations of crimes against humanity committed by both sides, including rape, torture and the use of child soldiers.

Millions are displaced and are facing severe food shortages due to a man-made famine, with the UN warning the country is on the brink of a "Rwanda-style" genocide.

Machar, who leads the opposing faction Sudan People's Liberation Movement-in-Opposition (SPLM-IO), claimed in a statement sent to IBTimes UK that the South Sudanese government "had a pattern of committing atrocities".

The rebel leader, who is currently in South Africa, also urged the international community to set up a "hybrid court of South Sudan" to try perpetrators of atrocities.

"We want to loudly reiterate that for a very long time, the SPLM/SPLA(IO) stood on the platform for peace, reconciliation, healing and forgiveness," read the statement.

"We think that for a national dialogue process to succeed, peace must prevail first and be accompanied by a process of accountability and justice."

The South Sudanese embassy in London has not replied to a request for comments.

Machar's remarks came one day after Kiir called for a national dialogue to, "save the country from disintegration and usher in a new era of peace, stability and prosperity."

In his speech, the president did not mention Machar or any plan to bring perpetrators to justice. However, he called on both sides to immediately cease hostilities and prepare, "the ground for a more peaceful, secure and joyous Christmas and New Year," AFP reported.

Kiir and Machar have agreed on several peace deals – the last of which was signed in August 2015 – but have failed to control their troops, who have broken every ceasefire since 2014.

Machar originally left South Sudan in 2013. His return, and his reinstatement, as vice president in April 2016 had restored hopes for the implementation of the peace process. However, he fled again following deadly fighting that left at least 300 people dead in Juba in July.

The rebel leader accused government forces of opening fire on his troops, and said he would return to the capital once a third-party force was deployed to ensure his and his officials' safety. He was replaced by Taban Deng Gai, a former ally of his.

Machar, however, still considers himself as the vice-president of South Sudan and exclusively told IBTimes UK he was ready "to go home".

A 14,000-troop-strong Unmiss (UN mission in South Sudan) was accused of not doing enough to protect civilians in July.

Following the allegations of inaction, a UN probe concluded Unmiss had failed to protect civilians due to "a lack of leadership on the part of key senior mission personnel".

The probe resulted in the sacking of Unmiss chief, Kenyan Lieutenant General Johnson Mogoa Kimani Ondieki. The dismissal angered Kenya, which decided to withdraw its troops from the UN peacekeeping mission.

Following July's violence, the conflict has spilled into the Equatoria region, where several rebels are sheltering.