When 21-year-old Mauro Demetrio was arrested and allegedly racially abused in a police van last summer, he turned instinctively to his mobile phone. Demetrio recorded the encounter on video, and an officer was charged. Now campaigners are harnessing the potential of mobile technology in a wider bid to hold police to account.

Stop and Search UK is a new mobile app designed to monitor the use of police stop-and-search powers, blamed by many involved in last year's riots for stoking tensions. Recent figures have shown that black people are now 30 times more likely to be stopped under section 60 of the 1994 Criminal Justice Act.

The free app allows those searched to log an electronic record of the incident, including the officer's badge number and the area where it happened, and rate their experience. Each upload is mapped by location and can be viewed by anybody who has the app; the data will eventually be published online. The app also provides a guide to what the police can and cannot do during stops.

The idea was piloted for Android mobiles in 2010, but developers Aaron Sonon, Satwant Singh and Gregory Paczkowsk expect the new BlackBerry version, to find a bigger following. "The main mobile phone young people use is BlackBerry because of BlackBerry Messenger," says Singh, referring to the messaging service that was used in last summer's riots.