Musicians have added their voices to calls for restrictions on the use of facial recognition technology at concerts.
Former Rage Against the Machine member Tom Morello and band Speedy Ortiz have joined a campaign by digital rights group Fight for the Future.
They want Ticketmaster to roll back its plans to use facial recognition as an alternative to tickets at events.
They argue it could be used to target music fans.
In a tweet, Tom Morello said: "I don't want Big Brother at my shows targeting fans for harassment, deportation or arrest."
Fight for the Future added: "Music fans should feel safe and respected at festivals and shows, not subjected to invasive biometric surveillance."
"Facial recognition is a uniquely dangerous form of surveillance. It enables ubiquitous monitoring of an entire crowd and could easily be used to target music fans for things like minor drug possession, immigration status, or having a warrant."
Ticketmaster's parent company Live Nation announced in May 2018 that to stop fans having to use tickets, it was teaming up with Blink Identity, which uses technology to scan people's faces as they enter concert venues.
While that would undoubtedly add to convenience and cut down on queues, there have been some unintended consequences of using such technology in the past.
And in the UK, London's Metropolitan Police Service admitted it had supplied images for a database used to carry out facial recognition at a development of shops and offices.