The Togo party were en route to their base in the region for the African Nations Cup, which is due to start on Sunday, when they were attacked with machine gunfire just after crossing the border.

Cabinda is separated from Angola by a strip of territory belonging to the Democratic Republic of Congo. It was formed from three kingdoms - N'Goyo, Loango and Kakongo - and was under Portuguese rule from the 19th century until 1974.

The following year, the Treaty of Alvor integrated Cabinda into Angola but it was a controversial move that was not accepted by any Cabindan political organisations and the government went into exile.

Huge offshore oilfields were discovered in 1967 and the distribution of Angola's oil wealth is one of the main sources of tension in the region.

An organisation campaigning for Cabindan independence, the Front for the Liberation of the Enclave of Cabinda (FLEC), began an armed struggle while the province was still under Portuguese rule.

That continued when Angola took control in 1975 and following the end of the Angolan Civil War in 2002.

The Angola government have said FLEC are no longer operative but this attack has highlighted the continuing unrest in the region.