South Sudan's President Salva Kiir appointed former rebel leader Riek Machar as the country's first vice president on Friday, a day after the two men agreed to form a government of national unity.

"I President Salva Kiir Mayardit, president of South Sudan, do hereby issue a decree for the appointment of Dr. Riek Machar Teny as first vice president of South Sudan with immediate effect," said a statement read on state television.

Machar is due to be sworn into office on Saturday, alongside three other vice presidents appointed to their roles on Friday.

Kiir also dissolved the country's cabinet. He appointed a new minister of presidential affairs and a national security adviser. The rest of the cabinet is expected to be named on Saturday.

On Thursday, Kiir and Machar, two former rivals, agreed to create a unity government before a February 22 deadline, paving the way for today's appointment.

A previous November 12 deadline was pushed back as key aspects of a 2018 peace agreement, including agreements on the number of states and unification of the army, had not been met.

This led the United States to impose sanctions on some political leaders.

But last Saturday, Kiir agreed to reduce the number of states to 10 from 32, a crucial opposition demand.

Other components of the peace agreements remain outstanding. Kiir said on Thursday that they would be finalized in the coming days.

Oil-rich South Sudan secured independence from its northern neighbor Sudan in 2011 but plunged into civil war two years later. Fighting claimed an estimated 400,000 lives and sparked the biggest refugee crisis since the 1994 genocide in Rwanda.

The conflict was triggered by Kiir's sacking of his then deputy Machar, who proceeded to form a rebel faction against the government.