Civil rights campaigners on Thursday launched a smartphone app that can video record interactions between police and member of the public, and store them for potential use in legal action.

The free app, developed by the American Civil Liberties Union (ACLU), comes amid an upsurge in protests over a series of deaths of African Americans in custody or at the hands of white police officers.

Videos recorded using the Mobile Justice CA cellphone app can be sent to a local ACLU office as a way to report possible civil rights violations by police.

The app, available for Android and iOS phones, will ensure that videos are uploaded and stored even if the user's phone is lost, seized or destroyed.

"The concerns over police practices, including racial profiling and excessive use of force, are very real for communities across the state,'' ACLU of Southern California Executive Director Hector Villagra said.

"This app will help serve as a check on abuse -- whether by police officers, sheriff's deputies, border patrol, or other officials -- allowing ordinary citizens to record and document any interaction with law enforcement," he said.

The app also can be used to send alerts to others to go to a location to document an incident. A report detailing the event can be sent to ACLU using the app.

Protests in Baltimore following the death of a black man from injuries sustained in police custody turned violent earlier this week, and on Wednesday spread to other cities including New York.