Five soldiers have been killed in a shootout in South Sudan's capital Juba, army and former rebel officials said Friday, in the latest blow to a shaky peace deal.

Sitting behind a table in his downtown Khartoum office, Sudanese businessman Ammar Sajjad talks in a hushed tone about his son's detention at his college campus last year.

For hours the 19-year-old electronics student was repeatedly beaten in a small room by a group of fellow pupils, who Sajjad said were members of a "jihad unit" that was active at the college.

Sudan's President Omar al-Bashir, wanted by the International Criminal Court for alleged war crimes, has applied for a U.S. visa to attend the next United Nations General Assembly, an official said Thursday.

It would be Bashir's first visit to the United States since his 2009 indictment by the Hague-based ICC for alleged war crimes in Sudan's western region of Darfur.

Sudanese President Omar al-Bashir flew to Uganda Thursday, state media reported, in his first visit to Kampala since his indictment by the International Criminal Court in 2009 for alleged war crimes in war-torn Darfur.

The rare-two day visit to Uganda -- a signatory of the Hague-based International Criminal Court -- is aimed at boosting often-fraught ties.

Nineteen Ethiopian children who were kidnapped last month by South Sudanese gunmen have been released, the Ethiopian government announced Tuesday, with negotiations underway to free dozens of others.

Dockers began unloading tens of thousands of tonnes of food from a U.S. aid ship on Thursday destined for war-torn areas of Sudan, an AFP correspondent reported.

The bulk carrier Liberty Grace docked in Port Sudan on the Red Sea coast with a cargo of 40,500 tonnes of sorghum, a staple food in Sudan.

Sudan insisted on Monday it had "sovereign rights" over two border territories whose ownership has been the subject of a long-standing dispute between Cairo and Khartoum.

Sudan has regularly protested at Egypt's administration of Halayeb and Shalatin near the Red Sea, saying they are part of its sovereign territory since shortly after independence in 1956.

Sudan said on Tuesday the result of a referendum in Darfur shows that the conflict in the war-torn region that has killed tens of thousands of people is finally over.

On Saturday, officials announced that almost 98 percent of Darfur voters had opted to keep the region as five states in a referendum that was boycotted by the opposition and criticized internationally.

Sudan's conflict-hit Darfur region starts voting Monday on whether to unify its five states, a long-standing demand of rebels seeking greater autonomy, but ongoing instability means insurgents are boycotting the referendum.

The three-day vote is expected to maintain the five-state system, which President Omar al-Bashir's ruling party says is more efficient but which observers say gives Khartoum greater control over Darfur.

Sudanese President Omar al-Bashir has said that he will step down in 2020 after his current term in office ends.

"In 2020, there will be a new president and I will be an ex-president," Bashir said in an interview with the BBC broadcast on Thursday.