Pietersen said he was left out the Natal side in 2000 because of the prevalent quota policy and that led him making up his mind to seek his career in England.
''I was dropped because the quota system was brought into South African cricket to positively discriminate in favour of 'players of colour' and to fast-track the racial integration of cricket in the country,'' he said in an extract from his new book ''Crossing the Boundary'' being serialised in the Daily Mail newspaper.
''To me, every single person in this world needs to be treated exactly the same and that should have included me, as a promising 20-year-old cricketer. If you do well you should play on merit.
That goes for any person of any colour. It was heartbreaking.'' ''Even though it was very hard for me to take in at the time, it turned out it was the best thing that could have happened,'' the newspaper reported from Pietersen's book.
Pietersen could not believe when he was told that he was being left out of Natal team so that Goolam Bodi could play.
''I flew into a rage, flinging a water bottle across the dressing-room and shouting 'I'm leaving here'.'' He and his father tried to reason with Natal coach Phil Russell but failed.
Pietersen admitted that he had spoken to Nasser Hussain about the possibility of playing cricket in England when he played against the touring side earlier that season, and that by the time he fell out with Natal there was already considerable interest from several counties in England.
Some players advised him to go, but the decision finally came after a meeting with Ali Bacher, at the time the key man in South African cricket.
''He was rude to me in that meeting and he was rude to my dad. I had never met the man before. As far as I was concerned the least he could do was be polite.'' Bacher failed to offer any encouragement that things would improve. ''As soon as we left the meeting my dad said to me: 'You're going ... the quota system will never finish','' Pietersen said in his book.
Pietersen then rang Clive Rice, the Nottinghamshire coach, and agreed to join them.
''I wouldn't call it an agonising decision. It was well thought out. I've always been a confident bloke and I was sure I would be successful,'' Pietersen said of his decision to leave South Africa.
Pietersen said had he remained in South Africa he might not even be playing cricket now.
''I would have been frozen out of the system ... I would have gone out and done something else.''