The national system for sending emergency alerts to mobile phones in the UK will be tested again this September, the government has said. It will see compatible phones vibrate and make a siren sound for 10 seconds while displaying a message at 15:00 BST on 7 September, even if they are set to silent.

While the government's emergency alarm system is there to warn people of danger to life – the alert itself could put some vulnerable people at risk.

The 'Armageddon alert', which was first trialled in 2023, is sent to phones across the UK to ensure people are aware of a life threatening emergency in their area