The Home Office has been accused of "shocking incompetence" for leaving a legal loophole that prevents police from holding the DNA profiles of thousands of suspected sex offenders.
From October, police in England and Wales will be banned from indefinitely holding genetic information on people arrested on suspicion of sexual and violent crimes once they have been released without charge.
Police will be given the right to apply for data to be held for longer, the BBC reported.
But with this appeal process not yet in place, Labour said many forces are already following government directives to delete records ahead of the change of law.
Shadow home secretary Yvette Cooper said: "Theresa May's failure to prevent and deal with this incompetence shows she has not taken seriously enough the risks to rape convictions and crime from her policy."
The Home Office said: "Forces will be able to retain DNA from someone arrested and not charged for up to three years, but only with permission from the biometrics commissioner. And all DNA samples taken by police are checked against the national database before deletion."
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Chief executive of The Institute of Cancer Research Professor Alan Ashworth, comments on the Tumour Profiling Unit's research that will look at the use of DNA mapping in future cancer treatments:
None of this is science fiction. One would think in five or 10 years this will be absolutely routine practice for every cancer patient, and that's what we're aiming to bring about.
Genetic profiling of cancer is already being investigated at several laboratories around the world, but the new unit will pioneer its use in the clinic
The £3 million Tumour Profiling Unit (TPU) in London is to research the use of DNA mapping to identify patients' cancer strains. It is hoped the technique will pave the way for radical new forms of diagnosis, surveillance and targeted therapy.
One aim of the research is to develop "liquid biopsies" that search for free-floating cancer DNA in samples of blood. This can then be used to identify and monitor cancer sub-types that are likely to respond to particular drugs.
Another, controversial, proposal is the use of "mouse avatars" that mirror a patient's disease progression.
Tumour samples from patients will be implanted into mice which will then be observed closely to spot early signs of molecular change and resistance to therapy.
A new laboratory could set the stage for a revolution in personalised cancer treatment in the coming decade, it has been claimed.
The £3 million Tumour Profiling Unit (TPU) in London aims to obtain the genetic map of an individual's tumours, enabling medical staff to give exactly the right drugs to tackle the disease.
Scientists will also use state-of-the-art techniques to track cancers as they progress, mutate and develop resistance to drugs.
The work, due to start this year, is expected to pave the way for radical new forms of diagnosis, surveillance and targeted therapy.
Patient trials are envisaged that will not only provide personalised treatments but follow the molecular development of tumours over time and combat drug resistance.
Scientists have encoded all of Shakespeare's sonnets into DNA in a bid to show how it could replace USB memory sticks and hard drives as a way of storing data.
The researchers artificially produced segments of the 'life molecule' - which contains all the information for human life - and added their own data.
As well as the sonnets, they encoded a 26-second snippet of Martin Luther King's 'I have a dream' speech, a photograph and a scientific paper.
The technique could be useful for long-term archiving since no electricity is required to store the data and just one gram of DNA can theoretically hold two petabytes of data - the equivalent of about a million one-gigabyte hard drives.
Our Science Editor Lawrence McGinty explains why DNA, previously classed as having no obvious use, could in fact be used to fight off genetic disease.
Dr Ewan Birney, chief analysis co-ordinator on the Encyclopedia of DNA Elements project, known as Encode, warned that is still a long way to go with the research. He said: "This is not the 100 metres, we are not Usain Bolt. This is much more a marathon where we have to emulate Mo Farah."