South Africa captain Graeme Smith was banned for four One-Day Internationals for his team's slow over-rate during Wednesday's one-run win in the third match against the West Indies in Barbados.

Match referee Jeff Crowe found Smith in breach of Clause C1 for conduct contrary to the spirit of the game and he was penalised following a hearing in Trinidad, the International Cricket Council said in a statement on Friday.

The ICC said that because it was the player's second breach of this provision inside a year, the penalty was automatically upgraded from level two to level three.

"Graeme has been warned at a similar hearing last September when in breach and has been advised on numerous occasions that his over-rates are too slow, including being fined after the second ODI of this series," Crowe said.

Smith, as skipper, was also fined 30 per cent of his match fee for the slow over-rates in Barbados. His team mates were fined 15 percent of their fees.

The 24-year-old Smith has 24 hours to appeal against the ICC's decision. Subject to appeal, the ban will apply with immediate effect.

Smith's previous breach was also against West Indies, in the ICC Champions Trophy in England last September.

South Africa have an unbeatable 3-0 lead in the five-match series. The fourth game is in Port of Spain on Saturday.