A further 20 gymnasts have joined a group-claim lawsuit against British Gymnastics alleging a range of abusive behaviour, The Telegraph has reported.
Last month, a group of 17 former gymnasts served a "Letter of Claim" on the national governing body, alleging physical and psychological abuse from coaches.
The allegations in the lawsuit include "inappropriate use of physical force by coaches against gymnasts constituting physical assault."
The Telegraph said British Gymnastics had asked for an extension until Dec. 19 to respond to the letter's claims after failing to respond by March 25.
The report added that litigation firm Hausfeld and Co LLP, who are representing the former gymnasts, had granted British Gymnastics an extension to June 19.
"We're disappointed but not surprised that British Gymnastics have failed to meet the reasonable deadline we set," Claire Heafford, one of the claimants who last year helped to set up the campaign group Gymnasts for Change, was quoted as saying by The Telegraph.
"Every day that they delay, former gymnasts are denied the justice they so richly deserve -- and current gymnasts are at risk of similar serious harms."
Reuters has requested comment from British Gymnastics.
An independent review, led by Anne Whyte QC, was set up by UK Sport and Sport England in August to investigate the allegations and make recommendations to those bodies and British Gymnastics.
After the allegations were initially made public last year, British Gymnastics chief executive Jane Allen retired from her role.
British Gymnastics had said after receiving the letter of claim that it would "not be appropriate or fair to all parties" to make any comment until they had the opportunity for it to be fully considered.
The governing body had previously said it was fully supportive of the Whyte Review and would be prepared to act on its recommendations.