The United States on Friday warned of a threat to air travel between Southern Sudan and Uganda.
The State Department said that it had information that "regional extremists" may be targeting flights between Juba, Sudan, and Kampala, Uganda.
A statement which came amid nervousness about violence as Sudan faces a referendum in early 2011 on possible independence for the South warned travelers on that route to be vigilant.
The United States has long warned its citizens against traveling to Sudan. A 20-year civil war between the North and the South ended in a peace agreement five years ago. The country has continued to suffer widespread violence, including in its western Darfur region.