Indian skipper Saurav Ganguly said he was upset about Shane Warne's exit from the World Cup on Tuesday after failing a drugs test, hailing him as 'a champion of the game'.

Ganguly told a press conference: "It's really sad news for world cricket. To make it worse, it was the last World Cup of his career.

"I really don't know the final situation, on what basis he has been banned, but obviously all the players in South Africa will miss him."

Australia's Warne, the most successful leg spinner to play the game, was due to fly home on Tuesday after testing positive for diuretics.

Warne said he had taken the substance by mistake as part of his attempts to slim down and that it was not performance-enhancing.

Ganguly added that India were very careful about any medication they took.

"The boys are strictly following instructions and it has been going on well," he said.

"Some of us had the flu (on the recent tour to New Zealand) and we consulted the doctors."

The International Cricket Council announced in September that dope testing would be introduced at the cricket World Cup for the first time, in accordance with South African law. The sport has never suffered a major drugs scandal before.