Johannesburg - Credit rating agency Moody's Investors Service on Friday downgraded the SA National Roads Agency Limited's (Sanral) credit rating and placed it on review for further downgrade. The decision was driven by the deterioration in the company's cash flow, Moody's said in a statement. "This cash-flow strain has arisen from the prolonged delay in the realisation of e-toll revenue earmarked to repay Gauteng Freeway Improvement Project (GFIP) related debt, and casts doubt on the company's financial health in the medium term," it said. Moody's downgraded Sanral's long-term issuer ratings to Baa3 (global scale, local and foreign currency) from Baa2, and to A3.za (South African national scale) from A2.za. In the past five years, Sanral has acquired debt of R20 billion to finance the GFIP. Fifty percent of the debt was guaranteed by the government.