The government says the Union of Democratic Forces for Unity (UFDR) rebels are operating from Darfur with the support of the Sudanese authorities.

BBC: NEWS | Africa | French planes attack CAR rebels

That is our biggest concern in terms of maintaining unity and keeping Syria from being an operating base for terrorist extremists.

NEWYORKER: The Thin Red Line

The oilfield in Unity is run by the Greater Nile Petroleum Operating Company (GNPOC), of which 5% is owned by Sudan's state Sudapec, 25% by Canada's Talisman Energy Co TLM.

BBC: Sudanese rebels