JUBA, South Sudan (AP) — South Sudan's ruling party has dissolved its leadership secretariat in a move that could raise political tensions following a peace deal with rebels, a presidential spokesman said Saturday.

President Salva Kiir remains chairman of the party, known as SPLM, and will appoint a new leadership at an upcoming national convention, said Ateny Wek Ateny.

The decision reverses steps made toward reunifying the party, which ruled South Sudan as a de-facto one party state since independence from Sudan in 2011 but splintered two years later with the outbreak of a rebellion.

Kiir head the government, while his former deputy, rebel leader Riek Machar, leads an armed breakaway faction.

Kiir is trying "to split the SPLM permanently" by dissolving the party's leadership body, said James Gatdet Dak, a spokesman for Machar.

The factions signed an agreement in Tanzania earlier this year to reunite the broken party, but presidential spokesman Ateny said the Arusha agreement is now "nullified."

The convention will proceed next month even if Machar and Pagan Amum, an influential politician who leads a group of dissidents, are not present in Juba, the South Sudanese capital, he said.

The SPLM cannot wait any longer to adopt a new party constitution and register itself as stipulated by South Sudan's political parties act, he said.

Dissolving the party leadership is aimed at pushing Kiir's rivals to form their own parties, said Luol Deng of the Juba-based think tank Ebony Center for Strategic Studies.

Since December 2013, tens of thousands of people have been killed and more than 2 million have been displaced by South Sudan's conflict, according to the U.N.

Implementation of the August peace deal between Kiir and Machar is slow and fighting persists in some parts of the country.