NAIROBI, April 7 (Xinhua) -- Kenyan-based Bahraini athlete Eunice Kirwa has pulled out of the Boston Marathon race set for April 16 in the United States.

Kirwa, who is the current Olympic marathon silver medallist, said Saturday a back injury she picked up in training has not healed in time for her to resume her preparations and she has been forced to withdraw from the race.

"I have a back problem and it is not getting better fast. I have not trained well and it will not be good to compete in a marathon when am not 100 per cent fit. All the best to the other athletes," she said Saturday in Eldoret.

Organizers have also confirmed that there are other notable withdrawals, which include Sara Hall (sacroiliac joint injury) and European bronze medalist Jessica Augusto from Portugal due to a foot injury.

Defending champion Edna Kiplagat, 38, will be putting up her title for grabs. Kiplagat, who last year won in Boston and went on to claim silver medal at the World Marathon Championships believes she has enough strength to fend off any potential threat to her title.

"I love running in Boston. I made my debut last year and it was great. I hope to return and win the title once more. But there will be a lot of resistance from the rivals and it is what you expect as a professional athlete at this level of competition," she added.

Kiplagat will come up against fellow Kenyans Caroline Rotich, who won the 2015 Boston Marathon and Gladys Chesir, who makes her Boston debut after finishing runner-up in Amsterdam last year. With a half marathon personal best of 1:06:57, Chesir could be in the chase for the title.

Course record-holder Buzunesh Deba of Ethiopia will return to the scene of her 2014 triumph, while two-time Frankfurt Marathon winner Mamitu Daska will be making her third appearance in Boston.