The UK’s Emergency Alerts system will undergo a nationwide test in September as part of efforts to strengthen the country’s preparedness for a range of disasters.

The system enables urgent messages to be broadcast to a defined area when there is an imminent risk to life, such as wildfires or severe flooding. Other countries such as the US and Canada already have such a system in place.

During the test, mobile phones will vibrate and make a loud siren sound for roughly 10 seconds, even if they are set to silent. A message will also appear on phone screens, making it clear the alert is only a test. There are approximately 87 million mobile phones in the UK.

The test, which will take place around 3pm BST on 7 September, is needed to ensure the system is functioning as planned, the Cabinet Office said.

Every 4G and 5G enabled device in the UK should receive an alert. However, when the system was first tested in April 2023, a small proportion of users did not receive it. Customers on the Three...