South Sudan President Salva Kiir has sacked his finance and planning minister after just six months in office.

In a presidential decree on Friday evening, Kiir replaced Dr Bak Barnaba Chol with Daniel Awow Chuang.

South Sudan is primed to go to polls for the first time in December even as indications are that the election will be pushed back by at least two more years.

Chuang, an engineer, was a minister for petroleum just two years ago before he was sacked. He was later appointed as a technical advisor in the finance and planning ministry under Dr Bak.

Eng Chuang becomes the 12th minister of finance and planning since independence on July 9, 2011 - and the 20th since 2005 when South Sudan signed the Comprehensive Peace Agreement that marked its separation from the Arab north.

Dr Bak's sacking comes on the back of the country's civil service going six months without salary amid skyrocketing inflation.

In February, he angered a section of war veterans with comments after their protest over delays in payment of medical allowances.

Also read: South Sudan's new finance minister braving 'ghosts' and crocodiles

He also left Kiir fuming after admitting that the country had no money to meet the 400 percent pay rise government had pushed for in August.

Bak, 43, had been picked from the University of Juba where he taught economics. He arrived with a youthful vigour and rare boldness after apparently diagnosing corruption and endemic failure to deposit revenue collection into the Consolidated Fund.

But his economic reform policy triggered a quiet backlash. Matters rose to a head when Bak restructured operations at Nimule border post and sent several illegal revenue collectors packing.

He also ramped up the push for reforms in the payroll to drain the economy of 'ghost' workers and refused to clear several invoices, saying claims had to first be verified.

While Kiir initially supported the youngest minister he ever appointed - including issuing a presidential decree on January 15 to approve of the payroll reforms and forensic audit into claims worth millions of dollars - Friday evening's decision shows Bak was fighting a vain battle.

South Sudan has hardly had an economy. Its finance and planning ministry is the cash cow for the powerful, who lobby day and night for appointment that would give them powers over the central bank and national petroleum authority.