The UK visas agency has identified a number of suspected criminals overseas by cross matching its new biometric database of visa applicants with older police databases.

Among those identified in the cross matching scheme – which has been running for two months – are two applicants in Vietnam whose fingerprints matched those found on a crime scene over 20 years ago, while a UK rape suspect was recently arrested in Australia.

"As well as those wanted for questioning, there are people who are immigration compliant who may have a criminal record who obviously we want to keep out," said Mark Sedwill, international director of the UK Border Agency.

In exceptional circumstances an applicant wanted for a crime in the UK will be granted a visa so they can be arrested at the border, though this presents difficulties as the person's point of arrival can't be guaranteed.

More often police in the applicant's country will be notified as in the case of the man arrested in Australia.

The scheme is complicated as information held on IAFS – UK Visa's database – is of a high quality, while information held on IDENT1 – the police database – is less "clean" and sometimes contains only latent or partial fingerprints.

The visa application centres are run in a number of overseas locations by suppliers CSC and VFS global.

Once biometric details are collected from these centres they are transferred to the UK and stored on a series of databases, before being checked against police records.

The agency has already taken the sets of over two million visa applicants who want to come to the UK.

Measures passed in the Serious Organised Crime and Police Act 2005 enable "data mining" – the cross matching of databases – an increasingly common practice in law enforcement. The powers were extended in the Serious Crime Act passed last year.

The practice will be among a number examined in the Data Sharing Review, being conducted by Mark Walport, director of the Wellcome Trust, and information commissioner Richard Thomas, and due later this year.

"These measures really need to be going through a necessity and proportionality test before they are introduced," said Peter Sommer, security expert at the London School of Economics.