JUBA, South Sudan -- 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 critics say threatens the peace deal signed in August to end the country's two-year civil war.

The announcement in a late night broadcast by the state-run South Sudan Television said seven of the 10 previous governors have been reappointed along with 21 others to run the new administrative zones.

Kiir's move 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. That deal rests on power-sharing in the original 10 states between Kiir and Machar's sides, as well as other political groups.

The rebel leadership is consulting on their reaction to the president's action, Machar's spokesman James Gatdet Dak told The Associated Press Friday.

The decree is unconstitutional because it violates the signed peace agreement and because the parliament, not the president, has the power to change state borders, said Lam Akol, the head of South Sudan's official opposition, the SPLM-Democratic Change party.

The new states divide South Sudan along tribal lines and the opposition party will not recognize the new states, charged Akol.

Kiir first announced that he intended to create 28 states in October. At that time, the United States and top donors Britain and Norway said the move "directly contradicts" the government's commitment to the peace deal.

The president's action is "unfortunate" because it presents a "key challenge" to implementing the peace agreement, said the Juba-based activist group Community Empowerment for Progress Organization in a statement Friday.

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