South Sudan's Riek Machar eyes Salva Kiir's job
South Sudan's sacked Vice-President Riek Machar says he will challenge President Salva Kiir for the leadership of the ruling party so that he can run for president in the 2015 election.
Mr Kiir dismissed Mr Machar and the rest of the cabinet on Tuesday following an apparent power struggle.
He accepted Mr Kiir's decision to sack him, Mr Machar said.
On Thursday, the US raised concern that the sackings could threaten the stability of oil-rich South Sudan.
It became independent in 2011 after decades of conflict with the north, making it the world's youngest country.
Numerous armed groups remain active in the country.
Mr Machar said people should remain calm, and not give the president an excuse to declare a state of emergency.
"This is a constitutional mandate of the president to remove and form a government. This is within the powers of the president. There should be no violence," he said.
Mr Machar said he would run for the chairmanship of the ruling party, the Sudan People's Liberation Movement (SPLM), before South Sudan holds its first national election since independence.
"I have told my colleagues in the politburo that come the next elections in 2015, I would contest those elections," Mr Machar said at a press conference in the capital Juba, Reuters news agency reports.
He condemned Mr Kiir's failure to appoint a new government immediately after sacking the cabinet.
"We now have a vacuum and this has created apprehension," Mr Machar added.
South Sudan's top civil servant Abgon Agao said Mr Kiir would appoint a new cabinet "very soon", possibly early next week.
He believed that a "good number" of dismissed ministers would be reappointed to the cabinet, Mr Agao said.
In the meantime senior civil servants are running the country, one of the world's least developed.
In a statement on Thursday, the US state department said: "It is critical that South Sudan stay true to the vision it laid out for itself two years ago at its independence."
More than 1.5 million people were killed and a further four million displaced during the conflict between the south, where most people are Christian or follow traditional religions, and the mainly Muslim, Arabic-speaking north.
But the country has suffered chronic economic problems since then and its stability has been hampered by lingering rows over territory and oil with its northern neighbour Sudan.
The SPLM led the fight against Khartoum.
As well as the cabinet, President Kiir also sacked SPLM head Pagan Amum and 17 police brigadiers.
The president gave no clear reason for the move, but analysts say he and Mr Machar have been embroiled in a power struggle for months.
Both Sudan and the South are reliant on their oil revenues, which account for 98% of South Sudan's budget. But the two countries cannot agree how to divide the oil wealth of the former united state. Some 75% of the oil lies in the South but all the pipelines run north. It is feared that disputes over oil could lead the two neighbours to return to war.
Although they were united for many years, the two Sudans were always very different. The great divide is visible even from space, as this Nasa satellite image shows. The northern states are a blanket of desert, broken only by the fertile Nile corridor. South Sudan is covered by green swathes of grassland, swamps and tropical forest.
Sudan's arid north is mainly home to Arabic-speaking Muslims. But in South Sudan there is no dominant culture. The Dinkas and the Nuers are the largest of more than 200 ethnic groups, each with its own languages and traditional beliefs, alongside Christianity and Islam.
The health inequalities in Sudan are illustrated by infant mortality rates. In South Sudan, one in 10 children die before their first birthday. Whereas in the more developed northern states, such as Gezira and White Nile, half of those children would be expected to survive.
The gulf in water resources between north and south is stark. In Khartoum, River Nile, and Gezira states, two-thirds of people have access to piped drinking water and pit latrines. In the south, boreholes and unprotected wells are the main drinking sources. More than 80% of southerners have no toilet facilities whatsoever.
Throughout the two Sudans, access to primary school education is strongly linked to household earnings. In the poorest parts of the south, less than 1% of children finish primary school. Whereas in the wealthier north, up to 50% of children complete primary level education.
Conflict and poverty are the main causes of food insecurity in both countries. In Sudan, many of the residents of war-affected Darfur and the border states of Blue Nile and South Kordofan, depend on food aid. The UN said about 2.8m people in South Sudan would require food aid in 2013. The northern states tend to be wealthier, more urbanised and less reliant on agriculture.