Radcliffe won the London Marathon in 2002, 2003 and 2005
Britain's Paula Radcliffe has been forced out of the London Marathon after breaking a toe in training.
A three-time winner of the race, Radcliffe had been hoping to build on her victory in New York in November.
The marathon world record-holder, 35, sustained the break to her right second toe while altitude training in the USA.
"I am desperately disappointed especially as I was looking forward to running in front of the amazing crowds of spectators in London," she said.
Radcliffe had been suffering from a ganglion, a swelling that forms around the tendons or joints, on the same foot and it is believed that it may have put pressure on the toe by changing her foot dynamics.
"I am considering surgery to get myself totally healthy as soon as physically possible and ultimately prevent the bunion causing any future problems," she said.
Radcliffe has yet to return to the race since her victory in 2005, missing the next three years through various injuries and breaks for childbirth.
"This is a major blow for Paula. I know how much she wanted to run here this year, but luck just does not seem to be on her side," said race director Dave Bedford.
"Even without Paula however, the elite women's field for 26 April is still one of the strongest we've ever had."
Radcliffe's focus will now turn to the World Championships which are staged in Berlin in August.
Germany's Irina Mikitenko, Romanian Constantina Dita and Catherine Ndereba of Kenya are amongst the favourites for the London crown.