Sudan's currency fell to a record low on the black market on Monday as concerns grew over delays in implementing oil and security deals intended to ease tensions with South Sudan.
Traders said the pound dropped to 6.3 to the US dollar, down from around four to the dollar in September.
The country has been struggling with an economic crisis sparked by the loss of most of its oil production when South Sudan separated in July last year.
Monday's price was down from 6.2 pounds per dollar a day earlier, said one trader who blamed the drop on a shortage of US currency in the market.
"Many, many people are looking for dollars," he said, declining to be named because he operates illegally.
Another trader confirmed the record 6.3 rate and said the pound had begun falling again over the past 10 days on reports that the deals between Sudan and South Sudan could be in trouble.
"The people had great expectations for these agreements," he said, also asking for anonymity.
"I think the rate will continue going up."
In early August the pound gained eight percent on the black market, to 5.7 pounds per dollar, after Sudan and South Sudan reached an oil deal which included a financial package worth about $3 billion.
South Sudan offered the package to Khartoum as compensation for the 75 percent of its crude production lost when the South became independent.
They also agreed on fees for exporting the South's oil through northern pipelines for export. South Sudan halted oil production in January after accusing Khartoum of theft in a long-running fee dispute.
Sudanese President Omar al-Bashir and his South Sudanese counterpart Salva Kiir confirmed that and other agreements in a late-September signing ceremony, after the neighbours fought along their undemarcated frontier in March and April, sparking fears of wider war.
One of the pacts calls for a demilitarised border buffer zone.
But the African Union, which mediated the deals, said on November 10 that the two countries had been unable to agree on practical steps to implement the security arrangements.
It urged their "full and timely implementation", to enhance confidence and to enable the other deals to take effect.
Southern oil has yet to begin flowing through the northern pipelines.
An International Monetary Fund staff report this month said that a reform package adopted by Khartoum in June is an important step to restoring economic stability and reducing dependence on oil.
Among its measures to address the crisis, which has seen inflation jump to above 40 percent, the government raised taxes, began phasing out fuel subsidies, and raised social spending.
It also devalued the currency to narrow the gap between the official and black market rates.