South Sudan has accused Sudan of launching an “economic war” less than three weeks after the two countries split.

South Sudan's top negotiator, Pagan Amum, said Monday that Khartoum is demanding a fee of nearly $23 per barrel to transport oil through its pipelines. He called the fee “daylight robbery.”

Amum also accused Sudan of violating an agreement by issuing its new currency so soon after separation.

Khartoum began circulating the new Sudanese pound on Sunday, less than a week after newly independent South Sudan introduced its own currency.

Many South Sudanese still hold the old Sudanese pounds, and officials in Juba worry Khartoum will refuse to buy back the old currency.

Sudan's central bank said Sunday it had not reached an agreement with South Sudan about what to do with the old money.

The two Sudans are still at odds over several major issues, including borders, the future of the disputed Abyei region, and how to share oil revenue.

South Sudan now controls most of the oil wells that previously generated huge revenues for Sudan. However in order to export that oil, South Sudan must use pipelines that run north through Sudanese territory.

The disagreements have sparked fears of a new Sudanese conflict. The former northern and southern Sudan fought a 21-year civil war that ended in 2005.