New Delhi, March 2 -- A former South Sudan finance minister is the latest former government official arrested in a wave of detentions that analysts say shows cracks in the government of President Salva Kiir, who also faces an armed rebellion.

The latest arrest came Friday when Bak Barnaba Chol was taken into custody while attempting to cross the border into Uganda. His arrest followed that of another former minister of finance and planning, Marial Dongrin Ater, who was fired in August.

In the past week, a former central bank governor, a former undersecretary for the ministry of petroleum, and a general in the domestic intelligence agency previously posted to the same ministry have been detained.

The exact reasons for the arrests remain...