An imposed quarantine on people flying into the UK will add to the confusion of Britons trying to figure out their future travel plans, a consumer group has warned.

The Prime Minister has said it will “soon be the time” to bring in a period of quarantine in order to stave off Covid-19 infection from abroad.

The situation has been described as “chaotic”, with calls for the Government to set out a plan to support the travel industry through the crisis.

This is going to be a knife-edge balancing act, to try to ease the lockdown while preventing a second surge

Addressing the nation on Sunday night, Boris Johnson said: “To prevent reinfection from abroad, I am serving notice that it will soon be the time, with transmission significantly lower, to impose quarantine on people coming into this country by air.

“And it is because of your efforts to get the R down and the number of infections down here, that this measure will now be effective.”

Mr Johnson and French President Emmanuel Macron have agreed quarantine measures would not apply between France and the UK “at this stage”, according to a joint statement.

Downing Street issued the statement after the pair spoke on Sunday.

“The leaders spoke about the need to manage the risk of new transmissions arising from abroad, as the rate of coronavirus decreases domestically,” it read.

“In this regard, the Prime Minister and the president agreed to work together in taking forward appropriate border measures. This co-operation is particularly necessary for the management of our common border.

“No quarantine measures would apply to travellers coming from France at this stage; any measures on either side would be taken in a concerted and reciprocal manner.

“A working group between the two governments will be set up to ensure this consultation throughout the coming weeks.”

Mr Johnson did not mention arrivals by sea, and he did not make clear whether it would include passengers on internal UK flights or on flights from the Republic of Ireland.

However, The Times has previously reported that travellers from Ireland, the Channel Islands and the Isle of Man will be exempt from the quarantine.

It has also been reported that the plan is to impose a quarantine of 14 days, and Airlines UK said it had been told by the Government that the plan will be in place by the end of the month or early June.

A Government official said quarantine is “a few weeks away from happening yet”, adding: “What the scientific advice tells you is that when domestic transmission is high, imported cases represent a small amount of the overall total and make no significant difference to the epidemic.

“However, this can change when the domestic transmission rate of infection is low and people are arriving from countries with a higher rate of infection.”

The official said industry and business will be listened to but the “purpose is to stop disease being imported into the UK”.

The situation is chaotic: the guidance issued by the Government against travelling abroad is indefinite, and yet some airlines and travel companies are selling flights and holidays due to depart within the next few weeks

Rory Boland, editor of Which? Travel, said: “This news will add to the confusion that British travellers are currently facing when trying to work out whether they can travel as planned, safely rebook postponed holidays, and when they will receive the refunds they are entitled to under consumer law for cancelled trips.

“The situation is chaotic: the guidance issued by the Government against travelling abroad is indefinite, and yet some airlines and travel companies are selling flights and holidays due to depart within the next few weeks which carry no warning that they are unlikely to go ahead as planned.

“Airlines and holiday companies must now be given clear FCO guidance on what dates it is appropriate to sell flights and holidays for.

“The Government must also urgently produce a plan to support the travel industry through this crisis, so carriers and holiday companies can comply with the law and refund consumers without fear of going bust.”

Dr Peter Drobac, a medical doctor specialising in infectious diseases and an academic at the University of Oxford, said there is merit to the quarantine idea, but said it will require a lot of planning and infrastructure at a “really fragile” stage.

He told the PA news agency: “All the experience that we have from the countries that have been trying to do this suggests that it’s really hard and it’s really fragile.

“This is going to be a knife-edge balancing act, to try to ease the lockdown while preventing a second surge.”

Commenting on the enforcement of a quarantine, Dr Drobac said: “You can’t wave a magic wand and say we’re having a quarantine and expect it to work.

“There’s got to be a lot of infrastructure in place to make that effective.”

Dr Drobac, a global public health academic, said this quarantine plan would have been a “smart” thing to do in February and early March.

“And that might have made a really big difference,” he said.

On Saturday, Airport Operators Association (AOA) chief executive Karen Dee said: “Quarantine would not only have a devastating impact on the UK aviation industry, but also on the wider economy.”

The Times newspaper said that “authorities will conduct spot checks”, with punishments for those not adhering to the rules including “fines of up to £1,000” and deportation.