The exact wording of the message that will be used to trigger Sunday's nationwide test of the UK's new emergency alerts system has been confirmed.

At 3pm on Sunday afternoon phones will sound across the country as the government trials technology that could notify households of a major emergency unfolding near them.

Nicknamed the 'Armageddon' alarm, the message will be picked-up by mobile phones within range and will appear along with an alarm sound and a vibration that will last for up to 10 seconds.

Once the message has been received and the sound heard, all people need to do in order to clear away the test alert is to swipe away the message - or click 'OK' - on their phone's home screen in the same way that they would get rid of any other notification or 'low battery' message. After this devices can be used as normal.

The message that will appear on home screens in conjunction with the alarm sound will read:

"This is a test of Emergency Alerts, a new UK government service that will warn you if there’s a life-threatening emergency nearby.

"In a real emergency, follow the instructions in the alert to keep yourself and others safe.

"Visit gov.uk/alerts for more information.

"This is a test. You do not need to take any action."

The exact hour has been chosen to avoid clashes with football matches and the London Marathon when it is tested on the afternoon of St George's Day.

In the Premier League two games kick off at 2pm, meaning the alarm will sound just as the second half gets under way as Bournemouth host West Ham and Newcastle play Tottenham.

In the FA Cup, Brighton v Manchester United kicks off at 4.30pm, but fans travelling to the match will receive the test. Anyone who is driving, should ignore the alert in the same way they would a text message.

The mass race of the London Marathon, which starts from 9.30am, has an eight hour time limit. Anyone running with their phone, and hoping for a time of around five and half hours, will see, hear and feel the alert as they cross the finish line.

Once the system is live, officials say it will be deployed to warn people in the event of emergencies such as wildfires or floods.

The April 23 test is not the first trial of the system. Localised broadcasts have previously taken place in East Suffolk and in Reading and the same technology is used around the world including the US, Canada and the Netherlands.

While in Japan, it has been widely credited with saving lives during severe weather events.

Chancellor of the Duchy of Lancaster, Oliver Dowden MP, said: "At 3pm Sunday we’ll be doing a nationwide test of our new Emergency Alerts system.

"Getting this system operational means we have a vital tool to keep the public safe in life-threatening emergencies. It could be the sound that saves your life."

For the test to work, a device needs to be switched on and emergency alerts settings activated. They are usually on by default, so anyone who wants to opt out would have to find emergency alerts in their phones settings and switch them off.

Once up and running the technology will allow an estimated 90 per cent of mobile phones in a defined area to receive the crucial updates.

While the government is encouraging people not to switch off the alerts, victims of domestic abuse who may be keeping a concealed phone are being reminded to take extra care with the notifications.

Women's Aid is among the charities reminding people with hidden devices to ensure they've opted out before Sunday.

Lucy Hadley, head of policy at Women’s Aid, said: "We are concerned about the impact of the emergency alerts system on survivors of domestic abuse. For many survivors, a second phone which the perpetrator does not know about is an important form of communication with friends or family – as some abusers confiscate or monitor and control their partner’s phone. It may also be their only lifeline in emergencies.

"The emergency alerts pose a risk, not only because an abuser could discover a survivors’ second phone, but also because they could use this as a reason to escalate abuse. At Women’s Aid we are working with our members and using our direct services to ensure that survivors who we come into contact with will be informed, and know how to opt-out of the alerts."

When fully up and running, the system will be used rarely, says the Government, and only when there is an immediate risk to people's lives.