An emergency alert being tested later could be the sound that "saves your life", the UK's deputy prime minister has said.

People across the UK will hear a loud alarm on their phones for about 10 seconds on Sunday at 15:00 BST.

Oliver Dowden said no action from the public will be needed, although some sporting events and theatre shows will be paused during the test event.

The new system will be used in cases of flooding, wildfires or terror attacks.

Mr Dowden reassured people they should not be concerned and will be able to "keep calm and carry on" with their day after getting the test alert on their 4G and 5G devices.

"It really is the sound that could save your life," the new deputy prime minister added.

He denied the testing of a new emergency national alert system on Sunday was an example of so-called nanny statism.

"I wouldn't accept that characterisation," he told the BBC's Sunday with Laura Kuenssberg programme.

He said the test of the system was a "bit like when the fire alarm goes off at work".

He said: "It can be a bit inconvenient and annoying.

"I think, in future, people will be grateful that we tested the system and what I would say is that at 3pm, when this siren - which I should say is about the volume of a phone call going off - goes off, you don't need to do anything.

"It is just a test."

He said: "The government's number one job is to keep people safe and this is another tool in the toolkit for emergency situations, such as flooding or wildfires, and where there is a genuine risk to life.

"So it really is the sound that could save your life.

"I would encourage people to remember that today it is just a test; there is no need to take any action and you can simply swipe it away as you would any other message you receive."

Those who do not wish to receive the alerts will be able to opt out in their device settings, while phones that are off or in aeroplane mode will also not receive one.

Ellie Butt, from the domestic abuse charity Refuge, is urging women who feel at risk to disable the alert.She said: "One in four women will experience domestic abuse in her lifetime... so it's safe to assume that there are a significant number of people that need to know that their safety might be at risk from these alerts, and they can opt out and turn them off."

The test message will say: "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."

People will then be prompted to swipe or click the message before being able to continue.

The test on St George's Day coincides with major events including the London Marathon and Premier League games between Bournemouth and West Ham, and Newcastle and Tottenham Hotspur, which kick off at 14:00.

Organisers of the World Snooker Championship have said they will pause play just before 15:00 at the Crucible in Sheffield and will continue it after the alert.

The Society of London Theatre also said it had advised members to tell people to turn off their phones to "minimise disruption to shows".

West End shows such as Harry Potter And The Cursed Child, Frozen, Mamma Mia! and The Lion King are among those putting on matinees on Sunday.

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