Southern Sudan, which will soon become an independent country, has asked the United States to lift oil sanctions on all of Sudan.

The south's vice president, Riek Machar, said Wednesday that the current sanctions will hurt the new country's ability to export oil because it must rely on the north's pipelines.

South Sudan is set to split from the north on July 9.

Machar spoke in Juba after arriving from the United States. He told reporters that the U.S. has promised to review the matter.

Most of Sudan's oil reserves are located in what will be south Sudan or in the disputed Abyei region.

Sudan is Africa's third-largest oil producer behind Nigeria and Angola.