By Mike Rowbottom at the Olympic Stadium in London

Alex Schwazer_August_7August 7 - Alex Schwazer's defence of his Olympic 50 kilometre race walk title on Saturday (August 11) ended before it had begun when he was withdrawn from the Italian team after failing a doping test – and announced his retirement.

The Italian Athletics Federation (FIDAL) announced Schwazer (pictured) has been pulled from their Olympic squad.

"FIDAL has received confirmation of the positive doping test of Alex Schwazer and the subsequent decision taken by CONI [the Italian Olympic Committee] to exclude him from their Olympic team," read a statement on the FIDAL website.

Schwazer told the Italian press agency ANSA: "I made a mistake, my career is ended here.

"I did it all myself and on my own head so I assume all the responsibility for what has happened."

The Olympic champion was also entered in the men's 20km walk that took place on Saturday (August 4) but withdrew last month, citing a cold.

At the time the 27-year-old made it clear he intended to defend his 50km title.

He won silver at the shorter distance in Beijing.

FIDAL president Franco Arese said: "Better that it happened before the race.

Alex Schwazer_at_Beijing_2008_August_7Happier times for Alex Schwazer as he celebrates his gold medal in the men's 50km walk at the Beijing 2008 Olympic Games

"If it had happened afterwards it would have been worse.

"We agree with CONI's decision to exclude him immediately from the Olympic team.

"He will be severely punished, as must be obvious, but I see from what he has said that he has had the courage to take full responsibility."

Arese added: "I can't understand what made him do it.

"I am sure he did not need to.

"One day I will ask him."

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