South Sudan's main opposition leader Riek Machar took the oath of office Saturday as the country's vice president, promising a better working relationship with President Salva Kiir.

"I want to assure you that we will work collectively to end your long suffering. It's our hope that the formation of the new government will create a new spirit of commitment for the implementation of the agreement," said Machar.

A 2018 peace agreement brought together the former warring parties in an expanded government known as the "Revitalized Transitional Government of National Unity."

It includes five vice presidents with Machar as the second most powerful man after President Kiir.

The new administration will have 35 ministries, ten deputy ministers, 550 members of parliament and aims to accommodate all the political factions in the country.

The swearing in of vice presidents was attended by several visiting African leaders.

Sudan's Sovereign Council Chairman Abdel Fattah al-Burhan, Uganda's Prime Minister Ruhakana Rugunda and South African Deputy President David Mabuza were among those in South Sudan's capital Juba for the ceremony.

Mabuza called on the parties to prioritize accommodating each other and resolving any pending issues.

"When we joined you and called on you to talk and resolve your current problems," said Mabuza, "we did it out of deep love for this country and its people."

The unresolved issues in the peace process include security reforms involved in unifying government and opposition forces, training and redeployment.

There is also still disagreement over state boundaries.

The formation of the new unity government is expected to end six years of civil war in the world's youngest nation.