Senior British police officials are talking to the FBI about an international database to hunt for major criminals and terrorists.

The US-initiated programme, "Server in the Sky", would take cooperation between the police forces way beyond the current faxing of fingerprints across the Atlantic. Allies in the "war against terror" - the US, UK, Australia, Canada and New Zealand - have formed a working group, the International Information Consortium, to plan their strategy.

Biometric measurements, irises or palm prints as well as fingerprints, and other personal information are likely to be exchanged across the network. One section will feature the world's most wanted suspects. The database could hold details of millions of criminals and suspects.

The FBI is keen for the police forces of American allies to sign up to improve international security. The Home Office yesterday confirmed it was aware of Server in the Sky, as did the Metropolitan police.

The plan will make groups anxious to safeguard personal privacy question how much access to UK databases is granted to foreign law enforcement agencies. There will also be concern over security, particularly after embarrassing data losses within the UK, and accuracy: in one case, an arrest for a terror offence by US investigators used what turned out to be misidentified fingerprint matches.

Britain's National Policing Improvement Agency has been the lead body for the FBI project because it is responsible for IDENT1, the UK database holding 7m sets of fingerprints and other biometric details used by police forces to search for matches from scenes of crimes. Many of the prints are either from a person with no criminal record, or have yet to be matched to a named individual.

IDENT1 was built by the computer technology arm of the US defence company Northrop Grumman. In future it is expected to hold palm prints, facial images and video sequences. A company spokeswoman confirmed that Northrop Grumman had spoken to the FBI about Server in the Sky. "It can run independently but if existing systems are connected up to it then the intelligence agencies would have to approve," she said.

The FBI told the Guardian: "Server in the Sky is an FBI initiative designed to foster the advanced search and exchange of biometric information on a global scale. While it is currently in the concept and design stages, once complete it will provide a technical forum for member nations to submit biometric search requests to other nations. It will maintain a core holding of the world's 'worst of the worst' individuals. Any identifications of these people will be sent as a priority message to the requesting nation."

In London, the NPIA confirmed it was aware of Server in the Sky but said it was "too early to comment on what our active participation might be".

The FBI is proposing to establish three categories of suspects in the shared system: "internationally recognised terrorists and felons", those who are "major felons and suspected terrorists", and finally those who the subjects of terrorist investigations or criminals with international links. Tom Bush, assistant director at the FBI's criminal justice information service, has said he hopes to see a pilot project for the programme up and running by the middle of the year.

Although each participating country would manage and secure its own data, the sharing of personal data between countries is becoming an increasingly controversial area of police practice. There is political concern at Westminster about the public transparency of such cooperation.

A similar proposal has emerged from the EU for closer security cooperation between the security services and police forces of member states, including allowing countries to search each other's databases. Under what is known as the Prum treaty, there are plans to open up access to DNA profiles, fingerprints and vehicle registration numbers.