Police are hoping to use crowd-sourcing to identify thousands of people suspected of committing crimes in last year's riots in London.
The Metropolitan Police are to upload almost 3,000 CCTV images of people during the widespread disorder in August last year onto its smartphone app.
The free Facewatch ID app developed with facial recognition software firm Facewatch and launched in April to identify people behind low-level crime, will contain 2,880 photographs which can be sorted via postcode.
The app then allows them to inform on people they see on it by sending a name and address straight to officers.
Assistant commissioner Mark Rowley, head of specialist crime & operations at Scotland Yard, said: “This is a great opportunity for the public to help us fight crime and bring those who remain outstanding to justice.
“My hope is that the two-thirds of Londoners who own smartphones will download this App, and help us identify people we still need to speak to.
“We need Londoners to browse through the App every week or so as new images will appear regularly. This is a fantastic way for Londoners to help us to fight crime.”
Almost 3,000 people have already appeared in court on charges relating to the riots in London and other areas including Bristol, Birmingham, Reading, Kent and Manchester last year.
They erupted after a protest in Tottenham, north London, on August 6, after 29-year-old Mark Duggan was shot dead by police, turned nasty.
Over the ensuing days violence swept across England leading to thousands of arrests.
The app, which was sponsored by BlackBerry manufacturer, Research in Motion (RIM), is available at the Apple App Store, Android Google Play and Blackberry App World for use on smartphones and tablets.
It will also include a further 2,000 images of people wanted by the police for offences not connected to the riots.
The technology and its secure database system has also been made available by Facewatch to all UK police forces and officials say it will soon link to the Facewatch business crime reporting system, already available to businesses in London.
Simon Gordon, director of Facewatch, said: “We are extremely pleased to be the technology partner behind the Facewatch application and, by working closely with the Metropolitan Police Service team, to help in a small way towards creating a safer and more secure city - especially in such an important year for London.”