This is why your mobile phone will make a loud emergency siren noise later this month in Milton Keynes

Local police are warning people that their mobile phone will make a loud siren noise later this month as the government tests its new Emergency Alert system.

The system, designed to warn people of nearby dangers, will be tested nationally on Sunday April 23.

A Thames Valley Police spokesman said: “The system will warn people when their lives are in danger. An Emergency Alert is a loud, siren-like sound with a message on your mobile phone screen.”

Reasons for an alert include severe flooding, fires and extreme weather.

Each alert will be accompanied with advice about how to stay safe.

A government spokesman said: “Working with mobile broadcasting technology, the Emergency Alerts system will transform the UK’s warning and informing capability; providing a means to get urgent messages quickly to nearly 90 percent of mobile phones in a defined area; providing clear instructions about how best to respond."

He added: “The system is now ready to be tested across the country following successful tests in East Suffolk and Reading, as the government continues to strengthen its resilience capability, making sure it offers the best possible protection against an ever-evolving range of threats.”

The government does not need to know your phone number or location to send you an alert.

The spokesman said: "Your mobile phone or tablet may make a loud siren-like sound, even if it’s set on silent.”

The phone may also vibrate and read out the alert, which will include a phone number or a link to the GOV.UK website for more information.

The sound and vibration will last for about 10 seconds.