Salva Kiir, the South Sudan president, has reappointed his rival, the rebel leader Riek Machar, as first vice president in a possible government of national unity.
"I, Salva Kiir Mayardit, President of the Republic of South Sudan, do hereby issue this Republican Decree for the appointment of Dr Riek Machar Teny as the first vice president of the Republic of South Sudan," the president said in a decree issued late on Thursday.
Speaking to Al Jazeera's Anna Cavell in the capital Juba, President Kiir's spokesman, Ateny Wek Ateny, said it was now up to Machar to decide whether to travel to the capital.
Ateny said that government forces were in the process of moving out of the capital, one of the steps agreed on to allow the formation of the transitional government.
"According to the presidential statement this morning, [Machar] has seven days to come to Juba - so they can expedite the process of forming the transitional government of national unity," Ateny said.
"That's what the president has asked him to do, as a very important partner to the peace agreement."
Machar had been Kiir's deputy until July 2013, when his sacking triggered a political crisis that later boiled over into a rebellion following a violent split among the security forces in Juba.
The rebel leader, who has been living in Ethiopia, welcomed the decree.
"It is welcome news because it is a step forward in the implementation of the peace agreement," Machar told AFP, speaking from Ethiopia.
Machar and Kiir signed a peace deal in August, although sporadic fighting has continued between government forces and rebels in some parts of the oil-producing East African country.
Both the government and rebel sides have been accused of perpetrating ethnic massacres, recruiting and killing children and carrying out widespread rape, torture and forced displacement of populations to "cleanse" areas of their opponents.
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Despite clashes and repeated failure to meet a string of deadlines in the deal, both Kiir and Machar have said they remain committed to the peace deal.
Despite the accord, both sides continue to seek new weapons, according to a report released last month by a United Nations panel of experts.
Kiir and Machar are former rebel leaders who rose to power during Sudan's 1983-2005 civil war between north and south, after which South Sudan seceded in 2011 to form the world's youngest country.