White, who therefore misses the Athens Olympics, said: “In doing this I have not only cheated myself, but also my family, friends and sport.

“I am sorry for the poor choices I have made.”

The United States Anti-Doping Agency (USADA) made the announcement in Colorado Springs, confirming what had already appeared in a leaked newspaper article.

The offences were a wilful contravention of the International Association of Athletics Federations (IAAF) anti-doping rules.

White began her suspension two days ago on the date she accepted the sanction.

All her competitive results achieved since December 15, 2000, have now been expurgated from competition records.

The ban means White will forfeit the cash prizes she should have earned for winning the world titles, which was never paid when modafinil was discovered in a drug sample she undertook in Paris.

Terry Madden, USADA chief executive officer, stated: “Ms White has made mistakes but I admire her courage in acknowledging these mistakes and accepting responsibility for them.

“It is not easy to admit you have done wrong and then stand up to do something about it.”

White, who has agreed to assist USADA in its efforts to clean up the sport, intends to seek early reinstatement from the IAAF as provided in the IAAF rules.

IAAF media director Nick Davies, commenting on the ban, said: “We commend USADA for the speedy and efficient resolution of this case according to IAAF rules.

Davies explained it was too soon to discuss the possibility of White making an early return to the sport.

“There is a provision in the IAAF rules regarding early reinstatement for athletes who have provided substantial assistance to a Member Federation in a doping case, but normally an athlete will be expected to serve at least a year of a suspension before seeking Council approval for this,” he said.