Millions of mobile phones across the UK will emit a loud alarm and vibrate as part of a national emergency alert test later this month.

The government and emergency services have launched the new system, which gives them the capability to send an alert directly to mobiles phones when there is a risk to life.

The national test of the Emergency Alerts service is scheduled to take place on Sunday 23 April at 3pm, when a siren will go off on nearly every smartphone in the UK for 10 seconds of sound and vibration.

The new scheme is similar to that used in many other countries and aims to warn people of extreme weather events such as flash floods, wildfires or extreme weather. It could also be used during terror incidents or civil defence emergencies if the UK came under attack.

The government says the alert would only be used in situations where there was an immediate risk to life. Only the government and emergency services will be able to send them and in most cases, it will be targeted at very specific areas rather than the entire country.

The test message and alarm is aimed at compatible phones. Phone users can either swipe away the alert message or click ‘OK’ on their home screen to continue using their phone as normal.

People who have their phones switched off will not receive the message - but it will sound if your phone is switched to silent.

All 4G and 5G Android and Apple phones are already fitted with emergency alert capability, as similar systems are in use in the United States, Canada, Japan and other countries around the world.

The alerts do not track your location, need your phone number or collect personal data, the government said. Anyone who does not have a mobile phone will be kept informed of emergency incidents in their area via other channels.

The alert will make a loud, siren-like sound. A message will appear on the screen giving information about the emergency and how best to respond.

People who do not wish to receive the alerts will be able to opt out in their device settings, but officials hope the life-saving potential of the messages means that users will keep them on.

Domestic abuse charity Refuge is advising vulnerable people to turn the alert off ahead of the test.

The charity tweeted: “If you’re a survivor of #DomesticAbuse with a secret or secondary phone, the government’s new #EmergencyAlerts could reveal your phone, even if it’s on silent.”

Due to the potential risks, Refuge has shared a video with instructions on how to turn off the emergency alerts on both Androids and iPhones.

The Government said it has been actively engaging with organisations working with vulnerable women and girls to ensure they are not adversely affected by the introduction of emergency alerts.

The national domestic abuse helpline can offer support on 0808 2000 247, or you can visit the Women’s Aid website