Isabel dos Santos Promises Overhaul of Angola's State Oil Firm

"From a compliance point of view, it's going to make it harder," the banker said.

President dos Santos's mild, inscrutable public demeanor belies his tight control of the former Portuguese colony, where he has overseen an oil-backed economic and construction boom in the wake of a devastating 27-year civil war that ended in 2002.

However, the collapse in oil prices has hit the economy hard, sending the kwanza to record lows against the dollar, pegging back growth to around 3 percent and forcing the government to seek IMF assistance.

(Additional reporting by Herculano Coroado; Editing by Greg Mahlich)