His Mercatone Uno teammates did not start in protest and Paolo Savoldelli, second overall behind his compatriot overnight, refused to wear the Giro leader's pink jersey.

A distraught Pantani said: 'I have come back several times in the past but it will be difficult this time.

'I'm sorry for cycling, which again has paid an extremely high price, and I'm sorry for the fans. I think we've really hit bottom. I don't know what happened, I think there's something strange.' His sample showed a haematocrit (red blood cells) level of 52 per cent, exceeding the limit of 50 per cent.

Blood tests were introduced by the International Cycling Union (UCI) two years ago 'to safeguard riders' health', but they also act as a check on usage of EPO, which boosts the red blood cells which carry oxygen around the body.

Mercatone doctor Roberto Rempi said heat and altitude were the only possible explanations for the high reading. 'This is the third test Pantani had and there were no problems with the first two,' he said.

Mercatone sports director Giuseppe Martinelli said: 'All this seems excessive. It seems excessive to do tests just before the heavy Dolomites stage.' Pantani, who became only the seventh rider to complete a Tour de France and Giro double last year, cannot compete for 15 days.

After that period he faces another blood test at the Lausanne headquarters of the UCI. If his haematocrit level has dropped below 50 per cent he can race again.

'I cannot understand it. I had two tests in the past, and I had 46 per cent when I had the pink jersey of Giro leader,' Pantani said.

Giro director Carmine Castellano said in a statement he 'deeply regretted' Pantani's exclusion.

But he added: 'While acknowledging the seriousness of what has happened, the race organisers must stress that respecting the rules and protecting the athletes' health is to be placed above all else.' Pantani said after his victory in France last year he had won 'the cleanest' Tour because of French police activities against doping.

Last year's Tour was thrown into disarray by a major drugs scandal.

It began with the arrest of Festina team employee Willi Voet before the Tour began. The car he was driving was found to be carrying large amount of forbidden substances, including EPO.

The revelation led to the eventual expulsion of the Festina team and several arrests. French police cracked down to such a degree that there was a riders' strike and four Spanish teams quit the race.

Then Alex Zuelle, Armin Meier and Laurent Dufaux, Festina's Swiss riders, confessed to using EPO and each served a seven-month suspension.

Reuters