JUBA (Reuters) - South Sudan will refuse do to any business in the future with oil trader Trafigura if it is proven that the firm bought oil from neighbouring Sudan in the knowledge that the cargo was seized southern crude, its oil minister told Reuters.

Geneva-based Trafigura, the world's third-largest oil trader, bought oil which South Sudan claimed was seized by Sudan in an oil row between the two African countries.

"If it is confirmed, I'm not accusing them (Trafigura) because it must be confirmed by the court, (but) if they are the ones that bought the crude with the knowledge that the crude or commodity was stolen, and they went and agreed with Sudan, then it has spoiled any future relations or transactions with us," Oil Minister Stephen Dhieu Dau said late on Tuesday during a visit to Palouge oil field.

Land-locked, war-ravaged South Sudan must pump oil to the Red Sea via a pipeline across its northern neighbour to Port Sudan but both countries have been unable to agree on a transit fee.

Oil revenues account for 98 percent of the seven-month-old country's income.

Sudan has confiscated more than 6 million barrels of South Sudan's oil since December due to the row over oil transit fees, a South Sudanese official said last week.

On Tuesday, South Sudan said it had expelled the head of Chinese-Malaysian oil firm Petrodar, the main oil firm in the African country, after accusing Chinese firms of helping Sudan seize southern oil.