The intensified military coup rumors emerging from Nigeria, which is one of the world's biggest oil exporters, has unsettled oil markets.

Nigeria was once notorious for its military rule, but has not suffered a coup since 1993 and economic progress is the biggest factor keeping soldiers in the barracks.

Nigeria President Umaru Yar'Adua last month rejected the alleged coup scare in the country by distancing itself from the position of the People's Democratic Party (PDP).

The ruling PDP had raised the alarm that certain foreign interests, intent on creating instability in Nigeria with the goal of containing her rising international profile, were working in concert with a coalition of opposition politicians to topple the federal government.