Al-Obeid Marwih, a spokesman for the Sudanese foreign ministry, suggested the conference was trying to find ways to avert an imminent economic collapse in the oil-rich African state, the Sudan Tribune reported Wednesday.
The U.S. special envoy to Sudan, Princeton Lyman, warned last week of a "calamitous" collapse in South Sudan if donors could not figure out a way to help the fledgling nation.
South Sudan suspended oil production more than a year ago after Khartoum seized a portion of its oil exports over what Sudan said were unpaid transit fees.
Juba ships its oil to Red Sea ports through Sudan.
The oil transit fee issue was resolved as part of a cooperation agreement between the countries in September, but Khartoum said the pact could not be implemented until security issues were resolved.
The conference, Marwih said, will have a "negative impact" on the agreement because it would allow South Sudan to delay action on the security issues.