MELBOURNE, Feb 12 (Reuters) - Shane Warne returns to Australia later on Wednesday determined to clear his name and salvage his cricketing career after he tested positive for a banned substance and was forced to withdraw from the World Cup.

The leg spinner is expected to arrive at 0930 GMT in his hometown Melbourne where he will come face to face with newspaper headlines like "Is This The End?" and "Shane’s career in turmoil over drug allegations".

Warne has said he mistakenly took a banned diuretic before a one-day international against England in Sydney on January 23, but the Australian media criticised the controversial player, saying: "Ignorance and stupidity won’t hold water".

The 33-year-old is expected to appear before the Australian Cricket Board’s (ACB) Anti-Doping Committee next week to explain why he took the diuretic and argue mitigating circumstances.

If Warne is found guilty of doping, he could face a two-year ban under ACB rules, a penalty that would probably end his brilliant career. But the ACB said the penalty could be reduced based on evidence by the anti-doping committee’s medical adviser.

Since ACB drug-testing started in 1998 two players have been suspended, one for one month and the other 18 months.

Warne shocked the cricketing world on Tuesday when he held a news conference in Johannesburg, only an hour before his team began their World Cup defence, to announce he had tested positive for a banned substance.

The ACB has said the positive test is "preliminary and subject to confirmation", and that if Warne is cleared of doping it will seek his reinstatement to the Australian World Cup squad.

SECOND TEST

The ACB said the anti-doping hearing in Melbourne would be held once the results of a second drug test, or B sample, were received. The result of the B sample is expected on Friday.

But Australian Sports Drug Agency (ASDA) chief executive John Mendoza said Warne’s B sample was unlikely to provide a different result to the A sample.

"It’s never happened in the laboratory’s experience in Australia and once only worldwide (out of) millions of tests," Mendoza told Australian radio on Wednesday.

Yet Warne remains optimistic about returning to South Africa to play in the World Cup, arguing the diuretic is not thought to be performance-enhancing.

"I have never taken any performance-enhancing drugs and am confident that this matter will be cleared up very soon," Warne told reporters in Johannesburg.

Warne, who dislocated his shoulder on December 15, said he took a tablet to reduce fluid in his shoulder on the eve of his comeback match against England, but did not know it contained a banned substance.

Diuretics are on the banned drugs list because they can be misused to lose weight quickly in sports which have weight categories or to increase the rate that urine is produced and eliminated. Diluting urine makes it more difficult to detect the presence of a prohibited performance-enhancing drug.

Warne, the greatest leg spinner in history and who was expected to play a major role in the World Cup before retiring from one-dayers to concentrate on test cricket, has been on a fitness regime for a year, losing around 13 kilogrammes (29 pounds).

"I am proud to be in the shape I am in at the moment and that is due to nothing other than hard work and looking after myself with diet," Warne said.

CONTROVERSIAL CAREER

Warne has been at the centre of several controversies both on and off the field. In 2000 he was stripped of the Australian vice-captaincy after stories he had sent a lewd message to a nurse in England and in 1994 was fined for accepting money from an Indian bookmaker.

But for some cricket fans, including Australian Prime Minister John Howard, Warne’s performance on the pitch is the key issue.

Warne, the player of the match in Australia’s 1999 World Cup final win over Pakistan, has taken 291 one-day international wickets (sixth on the all-time list) and 491 test victims (second).

"My hope is that he will be back playing for Australia before long," Howard told Australian radio from New York where he is holding meetings with the United Nations over Iraq.

Australian Cricketers’ Association chief executive Tim May said from South Africa that the players’ association also backed Warne.

"(We will) support and assist Shane through this difficult period. The clear intention of the (ACB’s anti-doping) policy is to catch those cricketers who use performance-enhancing drugs and as such we are hopeful of a reasonable outcome for Shane."