But the Olympic gold-medallist and three times winner of the Tour de France prologue said that it did not mean the end of his career.

His Credit Agricole team chief Roger Legeay explained: "It is very sad for him but, unfortunately, Chris, who has never been very lucky, fell ill at the worst possible time early in June.

"He suffered from severe sinusitis and had to receive antibiotic treatment. To keep him in the team for the Tour would not have been good for him and would have stopped an in-form rider from being picked.

"It is not yet the end of an era as Chris has big ambitions for the Olympics and the world championships. But to start the Tour without him will be a strange feeling."

Boardman won the Tour prologue in 1994, 1997 and 1998, claiming the race leader's yellow jersey on each occasion.

This year's Tour starts from the Futuroscope theme park near Poitiers on 1 July.