KHARTOUM (AFP) - The impact of unrest in South Sudan on India's US$2 billion (S$2.55 billion) investment in the region's oil sector will be under discussion when New Delhi's Foreign Minister makes a rare visit to Khartoum this week.

"It will be featuring in the talks," India's Ambassador to Sudan S. K. Verma told AFP ahead of the two-day visit by External Affairs Minister Salman Khurshid.

But Mr Verma said the seven-week-old conflict in South Sudan was not the reason for Mr Khurshid's stop, which would focus more broadly on "the way forward" in India-Sudan relations.

"Our largest investment remains in the energy sector, petroleum sector," Mr Verma said, putting the value at around US$2.3 billion before South Sudan separated from Khartoum in 2011 with about three-quarters of the united country's oil production.

India's ONGC Videsh Ltd, a partner in two joint oil production companies in South Sudan, announced on Dec 26 that the companies had temporarily halted operations there because of deteriorating security.

Mr Verma said bilateral trade between India and Sudan reached about US$888 million in the fiscal year to March 31, 2013.

His country is the second-largest exporter to Sudan, after China.

India is one of the world's five biggest emerging economies, together known as the "BRIC" group, along with China, which is another major investor in the Sudan-South Sudan oil sector.

Mr Khurshid is to hold talks with officials including his Sudanese counterpart Ali Ahmed Karti, and will meet with members of the 3,500-strong Indian community.

Mr Verma declined to say exactly when Mr Khurshid will arrive in Khartoum but his visit will follow stops in Morocco and Tunisia.