South Sudan aims to seal a $200 million credit line from an international bank within three months to cover imports and bolster the local currency, a minister said, after an oil shutdown erased the source of almost all its hard currency.

In June, the newly-independent nation secured a similar deal for $100 million from Qatar National Bank (QNB), used to issue letters of credit for imports like food, fuel, building materials and medicine.

South Sudan, which seceded from Sudan last year under a 2005 peace deal, shut down its oil output of about 350,000 barrels per day in January in a row over how much it should pay to export through pipelines running through Sudanese territory.

The government still had about 20 per cent of the QNB credit line left and planned to use it over the next two months, Commerce Minister Garang Diing Akuong said.

The letters of credit allow importers to buy dollars at the bank rate of 3.16 pounds to the dollar - a big discount to the black market price, he said.

"For the last three months, a lot of business people were using this facility," Akuong told Reuters at the weekend.

The deal also helped the South Sudanese Pound strengthen on the black market over the last few months from around 5.5 pounds to the dollar to about 4.2 now.

Akuong said he expected the new credit line would be settled "within two to three months, maximum," but declined to reveal the name of the bank because it had requested negotiations proceed in a "cool and quiet manner".

Fluctuations in the South Sudanese Pound are watched closely by foreign firms active in the country including cell phone operators MTN and Zain, which do business in pounds and then struggle to convert them into dollars to repatriate profits.

In addition to QNB, prominent international banks operating in South Sudan are Kenya Commercial Bank, Equity Bank and an affiliate of Dubai Islamic bank.

The oil shutdown erased about 98 per cent of the landlocked nation's state revenues. It has almost no industry apart from oil after decades of civil war with north Sudan.

South Sudanese officials have said it could resume some oil production by the end of the year but restoring full output could take until midway through next year.

Stabilising the pound in the longer term will depend on the country boosting currently meagre exports, Akuong said.

South Sudan loses about $1 billion a year in hard currency to neighbouring Kenya and Uganda through remittances, informal trade and imports of goods as diverse as medicine, cement, clothes, furniture and food, he said. – Reuters