Shane Warne announced on Tuesday that he is pulling out of the World Cup after it was discovered that he had been "inadvertently" taking a banned drug to treat his injured shoulder.

The announcement came shortly before Australia met Pakistan in its first match at the Wanderers.

Warne, 33, is to return home without bowling a single ball in cricket's showpiece tournament.

Warne told a press conference: "I have never taken any performance-enhancing drugs or intend to do so. I am sorry this had to happen, but I wish the team all the best."

"I was shocked and devastated when the findings were revealed to me last night. I was shocked because I 've never taken performance-enhancing drugs. I am proud to be in the shape I'm now but that's nothing to do with drugs. It's all due to my own hard work."

Australia's media manager, James Sutherland, said the banned substance had been found by the ACB in Australia as part of a routine test.

"The results are preliminary.

"We found it to our benefit to inform the ICC's anti-doping committee. Meanwhile, we have decided it was in our interest to send Shane back and wait for the confirmation."

The team has made a special request to the ICC whether it could include a replacement for Warne in the team, Sutherland said. We will request the ICC to reinstate Shane if  a more detailed inquiry absolves him." 

Australian television reported that Warne took diuretics while receiving treatment on his shoulder. Diuretics are banned by most sporting bodies, including the International Olympic Committee.

Diuretics were included in a list of banned substances that the International Cricket Council sent out, sports consultant Anant Joshi told a news channel in Mumbai.

Diuretics are used predominantly to express fluids from the body. However, they can also be used as masking agents for other drugs by effectively flushing them out of the system, or to help with weight loss.

Warne dislocated his right shoulder in a fielding accident on December 15. He made a quicker than expected recovery and returned to the team in time for the VB Series finals against England in Australia late last month.

Warne joins two other Australian cricketers to test positive for banned drugs -- West Australian fast bowler Duncan Spencer, who was banned for 18 months for taking the steroid nandrolone, and New South Wales batsman Graeme Rummans, who received a three-month ban for the antibiotic probenecid.

Commentator Mark Nicholas said Warne "tested positive" during the second one-dayer against England in Sydney, on January 22, in the VB series, but the findings were revealed only now.

Earlier report: Warne pulls out of World Cup