Angola and the Democratic Republic of Congo (DR Congo) are at loggerheads over access to offshore oil.
DR Congo, which produces relatively little oil - largely due to years of fierce internal conflict - has told the Reuters news agency that a border dispute between the two countries is depriving it of as much as 200,000 barrels a day.
The two countries are in talks over the dispute, which DR Congo says is blocking its access to deepwater blocks it holds offshore.
Angola, in turn, says it has sent technical experts to work with its Congolese neighbours to reach a solution.
Congo's oil industry may still be small - about 25,000 barrels a day are retrieved offshore, in collaboration with Total SA and ChevronTexaco. But Angola is rapidly becoming one of Africa's oil powerhouses.
Its current 900,000 barrel a day production is expected to double in the next five years, and oil majors are eagerly prospecting off the Angolan coast.
The income from the trade is great enough to have triggered rows with the International Monetary Fund, which has accused senior officials of creaming off as much as a billion dollars a year from oil revenues.
But while Angola has a confortably long coastline, the mainly landlocked DR Congo only touches the Atlantic for 22km, one cause of the current dispute.
In Ituri, many of the combatants are barely into their teens
Hard road inland
There are other potential sources of oil inland, particularly in the north-eastern province of Ituri.
But the opportunities for exploring and exploiting them are limited while fighting rages between ethnic militias in the area, following the pullout of Rwandan and Ugandan troops earlier this year.
Still, as has been the case with the rest of DR Congo's rich resources - such as gold, copper, coltan, diamonds and timber - the fighting has not stopped attempts to exploit the potential for oil.
One company, Canada's Heritage Oil, has rights to prospect in Ituri, as well as a deal with neighbouring Uganda to seek oil just across the border.