South Sudanese President Salva Kiir has abruptly dismissed his vice president, Benjamin Bol Mele, who was seen as a potential successor.

Kiir has stripped Bol Mele of his rank as a general and dismissed him from the National Security Service. He has also dismissed the central bank governor and the head of the revenue authority, who are said to be close associates of Bol Mele.

No explanation was given for the officials who were dismissed in a statement broadcast on national television.

The president made the decision amid growing fears that the country could descend into political instability and civil war after a recent power-sharing agreement between him and opposition leader Riek Machar collapsed.

Bol Mel, 47, did not express any regret at being removed from office.

In a letter to Kiir, he said, "I express my sincere gratitude for the opportunity you have given me to serve the people of South Sudan as Vice President."

Bol Mel was appointed as Vice President in February last year, replacing veteran politician and general James Wani Egan.