Planned changes to DNA retention will lead to less rape convictions, the victim of the 1986 Ealing vicarage attach has told politics.co.uk.
Jill Saward said that changes to the retention of DNA samples would be "very, very detrimental" as the government pushed ahead with the second reading of the freedom bill.
Under the proposed legislation, DNA would be stored for three years instead of Labour's proposed six years and would not be retained from anyone arrested but not charged with rape.
Ms Saward, one of the first rape victims to speak out publicly, described the proposed changes as "a very backwards move".
"It basically gives an ex-rapist a mandate to carry on," she told politics.co.uk. "Rapists know all about the advancements and the technicalities of what they can do and what they can't - cutting this down is just going to be so detrimental.
"I think it's a total disaster what they're planning."
Ms Saward has campaigned against sexual violence since burglars broke into her home at Ealing vicarage in 1986.
When the case came to trial, a judge handed down longer sentences for the burglary than for the rape, prompting Ms Saward to break her anonymity and write a book about her ordeal, Rape: My Story.
In 2008 she stood against Tory MP David Davis in a 2008 by-election because of his opposition to the government's DNA database.
Ms Saward criticised the pressures that she said would be placed on the police to crack cases within a three-year limit.
"If you cut it down to three years, it's hardly worth having in a sense because it often takes a long time. A lot of cases have been done historically; cold case reviews have come up with offenders. The time pressures on police to track people down in three years is just not feasible," she added.
"To deny people access to that information is wrong. I think it's a very sad move. Particularly in the case of stranger attacks, even if it's just 12%, that's still a big number, there are still a lot of people out there committing very violent attacks."
As the government plans to scale back DNA retention, Ms Saward called for a nationwide database.
"Ideally I would like to see a nationwide database, a universal database so that everyone was on it. It's a very backwards move what they're planning. I think if they introduced a national DNA database, it's not one rule for one and one rule for another; it's the same rule for everyone," she said.
On Monday, shadow home secretary Yvette Cooper raised concerns that the government's changes would make it harder to catch and convict rapists.
"The government is making it harder for the police to solve serious crimes. They are going too far in restricting the use of DNA from suspects who have been arrested," she said.
Ms Cooper suggested there would be 1,500 fewer detections as a result of the changes.
"Of course there must be safeguards in the system, but sensible use of DNA also helps catch very dangerous criminals and prevents innocent people being wrongly charged too. The evidence shows that too many serious crimes will go unsolved if they go this far," she added.
Rape cases have notoriously low conviction rates and the shadow home secretary cited the case of John Worboys to highlight the importance of the DNA database in securing convictions.
The cab driver stood trial for 23 counts of rape in 2009 and was eventually convicted on one count due to DNA evidence.
However, leading women's rights organisation Women Against Rape said that the DNA database can impinge upon human rights.
"DNA can prove innocence as well as guilt. But this can generally be settled by DNA taken at the time - there is no reason to keep it for years," the organisation said.
"For more than 30 years we have stood against attempts - by any party - to manipulate rape survivors' pain in order to attack human rights. When the rights of victims or defendants are undermined, this soon becomes the norm and justice can be denied to anyone."