JOHANNESBURG, September 10, 2008 (AFP) - Two South Africans were abducted earlier this week in Nigeria's restive southern Niger Delta region, an official statement said Wednesday in Pretoria.

'The Nigerian authorities have officially confirmed to South Africa's High Commissioner to Nigeria, Stix Sifingo, the abduction of two South Africans in the Niger Delta on Tuesday,' the department of foreign affairs said in the statement.

The statement neither gave the names of the South Africans nor the company for whom they worked.

'All I can say at this moment is that they are working in the oil sector in the region,' the department's spokesman, Ronnie Momoepa, told AFP.

Armed and criminal gangs operating in the oil-rich region have carried out a series of violent attacks on the oil industry and kidnapped hundreds of local and expatriate workers in the region since 2006.

Oil-rich Nigeria has seen a spate of kidnappings of local and foreign workers and relatives of prominent politicians in the past two years, often by gangs seeking a ransom, but sometimes also for political ends.

The unrest in the region has reduced Nigeria's oil output by a quarter, causing it to lose its position as Africa's biggest oil producer to Angola, according to April figures from the Organization of Petroleum Exporting Countries (OPEC).

The most prominent armed group in the region is the Movement for the Emancipation of Niger Delta (MEND).