Amber Rudd has claimed up to 1,000 people have been helped by the national inquiry into child sexual abuse, amid warnings of a "total whitewash".
The Home Secretary said it was "regrettable" that victims' group Survivors of Organised Institutional Abuse has formally withdrawn from the investigation after saying it is "not fit for purpose".
Other groups had already pulled out of the Independent Inquiry into Child Sexual Abuse (IICSA), including the Shirley Oaks Survivors Association, after raising concerns about the process.
Speaking in the Commons, Labour MP Lisa Nandy (Wigan) told Ms Rudd: "This is now really serious.
"This is the fourth victims' group that has left and today we have the Sutton Review, which reads to me like a total whitewash and suggests no lessons have been learnt by the inquiry or by the Government that set this up."
In an apparent nod to the Grenfell Tower tragedy, Ms Nandy added: "Can you tell me what message you think this sends to everybody in this country who is currently reliant on a public inquiry to deliver justice for them?"
Ms Rudd replied: "I'd ask you to reconsider your view. The inquiry has said the group can always come back if they want to.
"I'd ask you to think again about the people who are already being helped by this inquiry.
"There are 60 to 80 people whose experiences and whose attacks have been referred to the police, which may lead to prosecutions.
"That's up to 1,000 people whose lives have been changed and are getting the answers they want. That is real differences that I'd ask you not to underestimate."
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