South Sudan's President Salva Kiir made a Christmas Eve decree dissolving the nation's 10 states and creating 28 new ones, a move which may threaten the peace deal signed in August to end the country's two-year civil war.

Kiir announced the move in a late night broadcast by the state-run South Sudan Television.

Kiir's action to create 28 states comes after 150 rebels returned to the capital, Juba, on Monday to implement a peace deal signed by Kiir and rebel leader Riek Machar. Machar's spokesman James Gatdet Dak told The Associated Press that the rebels are consulting on their reaction to the decree.

South Sudan's war began in December 2013. Tens of thousands have been killed in the fighting that has displaced more than 2 million from their homes.