JOHANNESBURG, June 2 (Reuters) - South Africa's central bank governor Lesetja Kganyago said on Tuesday that the bank would bring inflation back to its 3% target, defending last week's rate hike as necessary to prevent second-round effects from the Middle East oil shock from becoming entrenched. The South African Reserve Bank raised its key repo rate by 25 basis points last Thursday, to 7%, with four out of six Monetary Policy Committee members backing the decision.