Engaged couples pinged by the Covid app on the night before they are married should call off their weddings, Number 10 has said.

Downing Street backed Vicky Atkins, the Home Office minister, who said brides and grooms had to stay at home if they were told to self-isolate by the app. This is despite the app having no legal force, which could make it difficult for families to claim on insurance for a postponed wedding day costing thousands of pounds.

Asked on LBC what a couple could do if they were "pinged the night before my wedding", Ms Atkins said: "Oh gosh. The guidance is ‘please, you must stay at home’. That is a terribly, terribly difficult scenario."

Asked whether it was fair that parents, relatives and grandparents cannot go to weddings if they are pinged, she added: "I totally understand how… the terrible impacts this virus has had on us all."

The Prime Minister’s official spokesman supported Ms Atkins’ comments, saying: "Yes we recognise that would be a difficult situation for anyone, but the app is carrying out an important function.

"One in three people contacted either by Test and Trace or the app go on to develop coronavirus. That demonstrates the importance of isolating people when asked to do so."

Over half a million 'pinged' at start of July

Chris Naylor, the chairman of the UK Weddings Taskforce and owner of the Boutique Hotel Group, told The Telegraph: "This is something we are seeing more of and it is extremely sad, unfair and frustrating, not only for couples but also businesses.

"We as businesses are already faced with staff shortages due to being pinged, but it takes it to another level when it is the bride or groom."

Mr Naylor warned that any weddings called off after the bride or groom were pinged would be unlikely to be covered by insurance, potentially leaving couples thousands of pounds out of pocket.

He said: "Unfortunately, we believe this isn’t something that will be covered by a wedding insurance policy currently. We must use our common sense and make small sacrifices in order to ensure that couples get the dream days they deserve and at the same time keep themselves, their loved ones and their suppliers as safe as possible."

Mr Johnson, taking part in Prime Minister’s Questions remotely from Chequers, where he is self-isolating, said: "I apologise to everybody in business up and down the land and in all kinds of services, public sector or otherwise, who are experiencing inconvenience."

He urged people to follow the rules until August 16 when the country shifts to "a system based on contact testing, rather than contact isolation", adding: "Until then, I must remind everybody that isolation is a vital tool in our defence against the disease."