Johannesburg:Graeme Smith quit as captain of South Africa's Twenty20 team with immediate effect on Wednesday, and said he will step down as skipper of the one-day team after the 2011 World Cup.
He will remain as the Proteas' test captain.
The 29-year-old Smith read from a pre-prepared statement at a media briefing at a Johannesburg hotel near the Wanderers cricket ground.
"There are several reasons why I have made this important career decision," Smith said. "I am going into my ninth season of international cricket -- eight as captain.
"It is my intention to play for another five or six years and I know in my heart that I can only do that if I give up some of my current responsibilities."
He said he was making the decision now to ensure "smooth transition."
The left-handed opening batsman, who was appointed captain in 2003 at a remarkable 22, added he remained passionate about the captaincy of South Africa and would continue to lead the test team with pride.
He said he would still be available for selection in all formats of the game, and "hoped to be around for quite a lot longer."
"In the shorter term ... all our efforts are now focused on winning the elusive ICC World Cup in February 2011," Smith said.
South Africa, which is regularly ranked among the best cricket teams in the world, has consistently underperformed at World Cups.
Cricket South Africa chief executive Gerald Majola, who was alongside Smith at the announcement, said: "I always respected Graeme Smith and I respect him and support him now. He took over the Proteas' captaincy at a young age, and has faced incredible challenges, which he has overcome.
"Graeme still has a lot to achieve in his cricket career and CSA backs him 100 percent," Majola said.
Majola said CSA had "a few players" they had been looking at as possible replacements and would make a new appointment within a month.
Smith added he would offer advice to South Africa cricket bosses as to who he thought his successor should be -- but declined to say publicly who he favored as the new T20 and ODI captain.
Spin bowler Johan Botha, who has led the team in Smith's absence, and batsman AB de Villiers are considered front-runners.
Smith said the decision to give up his captaincy was not easy, but he was "at peace with it."
"Someone said to me the other day that I had been captain of South Africa through my whole 20s and that came as a shock to me," Smith said, smiling.
"I hadn't thought about it.
"Making the decision was never easy. It's been such a large part of my life, (but) in many ways I'm at peace with it."
South Africa hosts India in three tests and five ODIs later this year. The countries are currently the top two ranked test teams in the world.
Before that, the Proteas play T20 and one-day series against Zimbabwe and Pakistan, starting in early October.