South Sudan accuses President Bashir of plot
South Sudan says it is suspending talks with Khartoum, accusing Sudanese President Omar al-Bashir of plotting to overthrow the southern government.
A senior official, Pagan Amun, said the plot was being orchestrated by the north's military intelligence. The north has denied the accusation.
The statement followed fighting between southern forces and a rebel militia in the southern oil town of Malakal.
South Sudan is to declare independence in July following January's referendum.
Mr Amum said the south's ruling Sudan People's Liberation Movement (SPLM) had details of a plan by Mr Bashir's National Congress Party (NCP).
"The NCP has been creating, training, supplying and arming militia groups in southern Sudan with the aim to destabilise and overthrow the government before July," he claimed.
"This plan is being overseen by the president of the republic Omar Hassan al-Bashir himself."
Earlier on Saturday, supporters of a renegade general leading a rebel militia in the south, Gen George Athor, attacked Malakal in the oil-producing state of Upper Nile.
It is the first major town to be attacked by the rebels. Eleven people are reported to have been killed.
Mr Amum also said the southern government was looking into ways of diverting oil routes that usually go through the north.
But a ruling party official in the north denied the accusation of a plot as "ridiculous".
Rabie Abdelati, a senior member of the National Congress Party added: "If the government of the south wants to export oil through any other means, it is up to them.
"We don't want to take something that is not ours," he told Reuters news agency.
Gen Athor went into rebellion after losing last April's election to be governor of Jonglei state, which he contested as an independent candidate.
His rebellion appears to be spreading, and represents a growing concern for the Southern authorities as they prepare for independence, our correspondent says.
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.