Scotland Yard should not be asked to take on additional functions following the upheaval caused by the phone hacking scandal, MPs have said.
In a report published on Friday, the Commons home affairs committee said the job of running the DNA database, the Police National Database, and the Police National Missing Persons Bureau, should not be given to London's police force.
"Given the recent upheaval and uncertainty at the Metropolitan Police, following the resignation of the Commissioner, Paul Stephenson, and Assistant Commissioner John Yates, we do not believe that it would be helpful, either for it or for the police service as a whole, for it to take on any additional national functions at this time," it said.
The job of running additional police services will be up for grabs once ministers phase out the National Policing Improvement Agency (NPIA).
The NPIA is due to be phased out in over six months but the committee said it was "unacceptable" that more than a year after the government announced the plan it had still has not revealed how its current functions would be distributed.
"We are not persuaded that the government can now meet this timetable and recommend that it delay the phasing out of the Agency until the end of 2012," the committee said.
Keith Vaz, the chair of the committee, said the government was engaged in the most radical shake-up of the police since the 1960s and among the most significant that have been proposed since Sir Robert Peel laid the foundations for modern policing nearly 200 years ago.
"We are deeply concerned that more than a year after the publication of the consultation paper, many of the details of the Government's proposals are still unclear," he said.
"This is extremely unhelpful, both for the police service itself and for the other bodies involved in the criminal justice landscape.
"The police perform a difficult and dangerous task on behalf of the public and the continuing uncertainty about the future of many of the bodies involved in policing has the potential to be very damaging."