The database is expected to hold details of about 100,000 people a year. It will not, however, contain the names of anyone who has previously run away or disappeared - information that has been vital in naming several of the Cromwell Street victims.
Police forces throughout England and Wales will send details of missing people to the bureau, which is based in a small office at Scotland Yard.
Three civilians with an annual budget of pounds 90,000 for their computers will record 'vulnerable' missing people who have not been accounted for after 28 days - most people return home within 48 hours.
However, children, the elderly, sick or suicidal would be logged immediately.
Details recorded will include descriptions, clothing and any other identifying features. The bureau will also log tourists who disappear in the UK and Britons who vanish while travelling abroad.
The Metropolitan Police, which is running the scheme with the Home Office, expects to reunite or trace almost all the missing people reported. It estimates that only 1,600 will remain unidentified each year.
Lord Ferrers, a Home Office minister, yesterday tried to deflect criticism that the scheme had taken too long to set up. The Council of Europe recommended in 1979 that every member state should have a national missing persons bureau. Five years later, the Association of Chief Police Officers (ACPO) made a similar recommendation.
Until yesterday, the only central data bank had been held by a small charity, the Missing Persons Bureau, which has had to change its name to the National Missing Persons Helpline. The bureau holds records of about 250,000 people reported missing; at least 100,000 are under 18.
Lord Ferrers said: 'It is wrong to suggest that nothing has been done - the difficulty has been to find a location. It (a national bureau) was identified in 1989 by ACPO, but it could not be done overnight.'
He added: 'The bureau is a major step forward. If it helps to find people who are missing and helps to alleviate the deep devastation of those who have loved and lost, it will have served a useful and humane purpose.
Deputy Assistant Commissioner David Veness, of the Metropolitan Police, added that the database would not have any 'sinister' use and that no one who had run away would be forcibly reunited. 'It's here to help people,' he said.
The Scotland Yard database is expected to be placed on the much larger police national computer - PNC2 - due to come on stream within the next few years.