April 3 (Reuters) - S&P Global Ratings:
* S&P lowers South Africa sovereign credit rating to BB+ from BBB-
* South Africa long-term foreign currency rating cut to 'BB+' on political and institutional uncertainty; outlook negative
* S&P on South Africa says "In our opinion, the executive changes initiated by President Zuma have put at risk fiscal and growth outcomes."
* Negative outlook reflects view that political risks will remain elevated this year, and that policy shifts are likely
* In addition, we lowered the long-term south africa national scale rating to 'zaAA-' from 'zaAAA'
* Believe sustained real exports growth likely to be slow over 2017-2020 because of persistent supply-side constraints to production
* Estimate that the change in general government debt will average 4.2 percent of GDP over 2017-2020
* Higher risks of budgetary slippage will also put upward pressure on South Africa's cost of capital, further dampening already-modest growth
* Reassessed S. Africa's contingent liabilities, reflects increased risk that nonfinancial public enterprises will need further extraordinary government support Source text (bit.ly/2nwCIRW)