The Japan-based runner was hoping for a return to form after two disappointing performances in 2010, in London last April and at the New York Marathon in November.

But with the London 2012 Olympics on the horizon, Britain's main hope for the race on April 17 – with world record holder and three-times winner Paula Radcliffe only just starting her return to training after giving birth to a second child - has been forced to concentrate on treatment and rehabilitation.

"I am very disappointed to have to withdraw from the 2011 Virgin London Marathon due to a hamstring injury," said the former Foreign and Commonwealth office diplomat whose personal best of 2 hours 23min 12sec has been bettered by just one other Briton – world record holder Radcliffe.

"London is an iconic marathon which I have enjoyed racing many times," Yamauchi added.

"I was looking forward to returning to London this April.

"But my injury treatment and rehabilitation must take priority, especially with the 2012 London Olympics approaching fast.

"I hope to return to my best as soon as I can.

"I wish everyone who competes on April 17 the best of luck."

Yamauchi was one of 15 women announced in the elite line-up who have a marathon best of less than 2:25.

She set her personal best when finishing second to Germany's Irina Mikitenko in 2009, a performance that appeared to herald a breakthrough.

But a series of injuries have prevented her reproducing that form since.

She missed the 2009 world championships in Berlin with a foot injury and could only finish 10th in London last year, exhausted by a six-day journey from her training base in the United States caused by Iceland's volcanic ash cloud.

She skipped last August's European Championships in Barcelona but lined up for the New York Marathon on November 7 with high hopes of finishing in the top three.

After racing with the leading group for the first half of the race, she faded to finish 13th in 2:31:38.

Virgin London Marathon race director Dave Bedford said: "It is a hugely disappointing to lose Mara from this year's race.

"Many in Britain were hoping to see her up with the medallists again, as she was two years' ago.

"It is a bitter blow for her, but we understand she needs to recover fully from this injury and prepare as well as possible for the Olympics next year.

"Despite Mara's absence, we still have one of the most talented women's fields ever for this year's Virgin London Marathon and are looking forward to a fantastic race."

Britain's hopes in the women's event now rest with Olympian Liz Yelling, the former Commonwealth Games bronze medallist, plus two marathon debutantes, Yelling's sister-in-law Hayley Yelling and seasoned international Jo Pavey.

Andrew Lemoncello, the Scotsman who was eighth on his debut last year, will fly the flag for Britain in the men's race, and will doubtless be targeting the newly-established UK Athletics qualification criteria for London 2012.

Although his London time last year of 2:13.40 is comfortably inside the B standard mark of 2:16, he only needs to run one minute and 40 seconds faster to earn an A qualifying mark.

Contact the writer of this story at [email protected]



Related stories
October 2010: New York Marathon hopeful Yamauchi "ready for anything
April 2010: Yamauchi tired but here at last - after losing her sanity in the Gare du Nord station...
March 2010: Yamauchi takes bite out of Big Apple
April 2009: Mara Yamauchi - If I keep improving I can win a medal at London 2012
June 2008: Yamauchi praises proposed London 2012 marathon course