The South African lender declared a dividend of 189 cents per share and posted a return on equity (RoE), a key measure of bank profitability, of 21.8%. South African lenders, one of the biggest in the continent, had a good run last year, but a worsening operating environment in the country, primarily due to frequent rolling blackouts, has raised doubts about sustainable growth. Increasing interest rates have led to worries of bank loans going sour in a country jostling with high unemployment and anaemic growth, and analysts have said FirstRand's primary exposure to South Africa could be a big risk. "Structural constraints in South Africa... will, however, continue to limit the growth opportunities," FirstRand said, but added its RoE for the next six months would remain at the upper end of its stated range of 18% to 22%. (Reporting by Promit Mukherjee; Editing by Muralikumar Anantharaman and Subhranshu Sahu)