The crisis is rooted largely in the secession of oil-producing South Sudan a year ago. The new nation took about three-quarters of Sudan's crude output, leaving Sudan with a budget gap, high inflation and a depreciating currency.
The two sides are meeting in Addis Ababa to discuss issues including how much the landlocked South should pay to export oil through pipelines and other infrastructure in Sudan - fees which could ease Sudan's crisis - but have so far failed to agree.
(This story is corrected after U.S. embassy said man not a U.S. citizen)
(Reporting by Khalid Abdelaziz; Writing by Alexander Dziadosz; Editing by Andrew Roche and Mark Heinrich)