Uganda has deployed special forces in South Sudan's capital Juba to "secure it", Uganda's military chief said on Tuesday, but South Sudan's information minister denied the presence of troops, as tensions between South Sudan's president and first vice president stoke fears of a return to war.

South Sudan's government has denied earlier reports that Uganda had deployed special forces to its capital, Juba. Uganda's military chief Gen Muhoozi Kainerugaba said the soldiers had gone to the neighbouring country to help South Sudanese President Salva Kiir "secure" the city.

The arrests in Juba and deadly clashes around the northern town of Nasir are seen as jeopardizing 2018 peace deal that ended a five-year civil war

Uganda has deployed an unknown number of troops to South Sudan in a bid to protect the fragile government of President Salva Kiir as a tense rivalry with his deputy threatens a return to civil war in the east African nation.